Now that the Zune
has upped the ante by including WiFi syncing out of the box, it looks like owners of other devices are starting to rig up solutions of their own -- and the iPhone setup developed by eddanx seems to come closest to the ease of the Zune. The system relies on the WinAmp plugin ml_ipod, which supports syncing to shared folders, and requires a jailbroken iPhone and a little SSH / SFTP softshoe. Of course, by giving up iTunes, you give up contact, calendar, movie, and phone syncing as well, but who cares -- you're wireless now, baby. Check the read link for the full instructions.
PS: We'd imagine this would also work on an iPod touch -- anyone care to try?