Joost, the much-hyped internet TV service created by the founders of Skype, is set to open up to the public today following several months of successful invitation-only testing. Users around the world will now be able to download the Joost client and use it to view professionally produced content on their PCs.

It remains to be seen whether Joost can make a splash among consumers. Mike Volpi, the former Cisco executive who joined Joost as chief executive earlier this year, told us over the phone last week that the site had about 1.5m registered users during its invitation-only phase, of which about 10 per cent were active. That’s a small user base, but an understandable one for an invitation only system. Now, with the gloves off, Joost is hoping to gain a wider audience by word of mouth. It is shunning a broader ad campaign (Volpi says the service has been hyped enough in the media). However, it has been moving to strike more content deals with partners including Viacom, Paramount and CBS.

Along with its move to open to the public, Joost is also announcing a move to open to developers. In a page right out of the Facebook playbook, it will open its APIs to allow outside developers to create widgets that lie on top of the service’s video player. The hope is that outside programmers will help contribute to an ecosystem of social features that allow Joost users to connect with each other to talk about content online.

Ultimately, Mr Volpi says, the real key for Joost is content. And not just professional studio content. Just as YouTube opened up an entire new genre of user-generated content, Joost hopes to offer a venue for smaller scale, but professionally produced, productions. "When producers hear about Joost, they say, ‘that’s great, I have three ideas I want to pursue for about $50,000 each, and if I did that can I put it on Joost?’ I think in the end  that is going to be a very interesting sweet spot for us." says Mr Volpi.