The site, which is retaining its beta tag to encourage feedback from users, was soft launched at the end of the summer, but has now made previously registration-only areas accessible on the open web.
Publish2's system lets users bookmark webpages and organise and share these links through a shortcut in their internet browser window.
These links can be tagged, edited and selected for republication on a news website as a feed or widget, which can be branded to match a site's own design as seen in the 'political picks' section of The News Tribune's site.
New features expected to launch this week include the ability for journalists to send selected links using the system to their accounts on microblogging service Twitter and social bookmarking site delicious.
Designed exclusively for journalists and with the input of working newsrooms, Karp hopes the platform's news group feature, which reporters can use to create a list of links around a news item, will create more editorial content for news sites without adding to the individual journalist's workload.
The system, he adds, could be used to involve 'print-side' journalists 'who aren't contributing much to the web', without adding to their responsibilities.
For a reporter to set up a blog, 'you've got an entirely new editorial responsibility,' he says. Whereas with this system 'it could be an easier way for a reporter to contribute something to the web', he explains.
"This is more lightweight, essentially link-blogging, and integrated into what you're already doing," says Karp.
"Newsrooms are laying people off, and you've got people taking editorial value [links to sources and research] and throwing it out."
"An individual newspaper could get their whole newsroom to do this and tap into what everybody's already reading and finding, and essentially create their own different wire services or just to publish these links on their website."
Key to the system is retaining editorial control over what links are published, says Karp, who adds that the BBC's trial of in-story links to only a handful of sources is not too limiting, but in fact the first stage of getting publishers into the practice of linking.
Links are for human judgment
"The link is an editorial judgment. It should be in most cases a human judgement, because you never know when an algorithm [used by some news sites to generate news links] is going to spit out a link and send people some place unreliable.
"There's a very legitimate concern about linking to unverified or unverifiable resources. It becomes a journalistic issue of 'can you trust the things you're linking to', because by linking to it, you are validating it."
The same fact checking process that is used by newsrooms for stories needs to be developed for links, he adds. As such, editors can have access and the final say over the links included in their title's news group on Publish2 before they are republished on a website.
Karp hopes this verification system for links can also be developed across newsrooms through Publish2's newswire feature - a wire of links tagged by other users, whose identities are open and who are confirmed by the site as journalists upon registration.
"If you find something on the newswire and another journalist or newsroom that you trust has linked to it, that's one layer of validation," he explains.
"If you think about how the traditional newswire works it's pre-vetted; the same process could happen with links, where there starts to be a vetting process across newsrooms, among journalists of stories and sources that are trustworthy."
Journalists and editors using the system collaboratively can develop themselves and their sites into 'filters for the web', as well as online publishers, according to Karp.
"This won't replace reporting, but act as a complement. The Washington Post hasn't abandoned political reporting [following the launch of a section of links to other political sites], this is something they're doing that is a complement. They can take the same brand that people trust and use it to filter other political content."
Mutual linking in the 'link economy'
Editors should not be scared of links to external content and competitors' sites, as this will create a stronger argument for your site as a destination for readers, explains Karp.
"This is what the traditional news brand could be doing: if they're consistently being a good filter for even your competitors, people will come back for it. That's the counter-intuitive thing about the web," says Karp, adding that Google and The Drudge Report have found great success in 'sending people away' and 'keeping them coming back'.
Mutual linking combined with news organisations acting as a guide to other news content online could have significant benefits for 'Journalism' as a whole, says Karp, adding that he is in talks with large newspaper publishers in the US about using Publish2.
"Traditional news organisations could have a huge impact by entering what Jeff Jarvis calls 'the link economy', because they do still have tremendous credibility and huge reach for audiences.
"If they start to get into this game they could have a huge impact on more attention getting paid to good journalism on the web. They can bring that trust factor back.
"If everybody sends each other traffic you're going to have a net increase in the amount of attention everyone pays to 'Journalism'."
Such a feature enabled by Publish2, says Karp, could help papers in the US break away from the Associated Press (AP) model, while still allowing them to provide relevant national news and regional news to readers.
"The AP story is a commodity, because it's published on 1,000 other websites too. If there's a particular story that breaks, a page of links to other interesting reporting [of that story] is probably of more value to the reader than the commodity story that they've already read in all those different places," he says.
Creating a 'newswire' of links across newsrooms is an extension of the content-sharing agreements already established by some US newspapers, such as the OHNO group.
Tailored news aggregation
Karp is also working on a form of advertising tailored to news aggregation of this kind, which he says could change the business model of the newswire for publishers.
"We're thinking about what could we do with news aggregation where the value that the advertiser brings to the table is the same as what the journalist is doing with Publish2 [filtering the web for interesting news].
The Publish2 widgets featured on newspapers' sites could then become a distribution network for advertising on a revenue-share basis, says Karp. Additionally, the service, which is currently free for newsrooms and journalists, will remain so to anyone who adopts it.
"What if you could take the newswire and turn it from a cost centre into a profit centre? So there's actually some revenue coming in attached to it as opposed to taking money away from your reporters.
"We want to add new opportunities rather than create obligations. That's what's happening with the AP: they made certain assumptions about what the cost of this service was, but that changed and now their own economics are rapidly changing and the whole equation gets blown to pieces."