1. Windows Mobile 6.5
Kicking off our countdown, the latest iteration of Microsoft's eternal runner up. Not an awful operating system as far as it goes, WinMo is just tremendously outclassed by its competitors.
Whether it's the charm of the iPhone, or the extensibility and permissiveness of Android, Microsoft's venerable mobile software is being outflanked, even in its traditional stronghold of business users. Even Steve Ballmer, CEO of Microsoft, says he has been disappointed with the recent efforts. While the folks in Redmond promise something special from Windows Mobile 7, some mobile vendors have gotten sick of waiting for them to pull an iPhone beater out of their hats.