Vodafone's CEO, Arun Sarin, has used his Mobile Wireless Congress speech to call for mobile OS consolidation. He's claiming it's a pain to develop for up to 30 different incompatible systems (though, in a clear reference to Microsoft, he also confirmed he didn't want just one).
Smartphone operating systems are such a new and rapidly developing field that it's not surprising there are so many. There will naturally be consolidation as the big players invest.
The theme of the 2008 Mobile Wireless Congress is supposed to be internet applications. That's a start, but still not clear enough. Let's hope the 2009 Mobile Wireless Congress theme should be web applications.