Symbian — the OS that runs in about 330m mobile phones on the market is not Open source and free. Non-profit Symbian Foundation consists of about 50 companies and was created by Nokia in mid-2008 followed by the acquisition of Symbian LTD. Lee Williams, executive director of the Symbian Foundation says that all source code is open now and the company is going to publish development plans up to 2011.
So we have 3 players: Google with half-open Android, Apple OS with closed iPhone OS, and now Symbian with fully open code.
At the end of the day, it all comes down to UX and it will be interesting to see what approach will be more beneficial to the end-user. Most of us care about how much can we do what we need to do and how easy it can be done. Right now iPhone OS looks like a clear leader in its simplicity and user satisfaction.