YouTube has been available for many mobile phones for over a year, now, YouTube is offering a new version of the mobile
YouTube application for more operating systems.
The Mobile YouTube is optimized for most Windows Mobile and Symbian
Series 60 devices (a list of supported Nokia S60 devices is available here). The mobile app is also much faster -- up to 90% faster starting up, searching, and video
loading. Better video quality is due to the video being automatically
optimized to the users of a W-iFi or 3G network.
To get the app, visit http://m.youtube.com from a supported mobile
device. They plan on more improvements in the future.