The Symbian Foundation has laid out its release strategy for future platform updates. If they are able to stick to the proposed schedule, there will be two platform releases each year.
First up will be Symbian^2 which is based on S60 5.1. Its feature set is apparently pretty much settled and should start to appear in devices by the end of the year. Symbian^3 will follow six months later. Work on the feature set for Symbian^4 is already underway. Each release will receive .x updates to fix bugs for a period of one year following release.
Nokia acquired Symbian at the end of 2008 and announced plans to turn over the Symbian and S60 software to the non-profit Symbian Foundation which will offer the Symbian Foundation platform to members under a royalty-free license.
Just one question: Where is Symbian^1?