Windows Mobile 6 Standard supports file sync - but not with Vista
And Windows Mobile 5.0 Smartphone edition lacks something that the PocketPC version has: the ability to synchronize files in your "My Documents" folder between your PC and phone.
Microsoft has decided to restore that feature in Windows Mobile 6 Standard (which is the name of the smartphone version). There's just one catch. It only works with ActiveSync. And ActiveSync doesn't work with Windows Vista. It's been replaced by Windows Mobile Device Center, which has no support for file synchronization.
So essentially Microsoft has issued two major operating system updates this year, but they aren't really designed to work well together. If you buy a new smartphone and a new computer, you're going to be penalized. Of course, you can always use 3rd party applications like Mobsync to synchronize your files.