Joost, the online television service from Skype and Kazaa founders Janus Friis and Niklas Zennstrom, launches today. Current beta testers will now get an unlimited number of invites, after being limited to five till now. A number of leading advertisers including Coca-Cola, Nike, General Motors and Visa will start ad campaigns this month. The latest version is available for download from existing users and those invited to join. While most of their content provided is aimed at US and UK audiences, there are plans to expand to Asia and Latin America. Let’s see how far they can get with PC-based TV before some bright spark invents the Joost TV plugin.