Leave it up to good old HTC to release the first full YouTube client for Windows Phone 7. Too bad it's only for HTC phones, but you knew that would be the case, right?
The app is surprisingly not yet listed in the HTC App Hub, but you can find it under Apps --> Music & Video --> New for now. Overall, the design of the program is very similar to the old Windows Mobile version but with the panoramic styling of Metro. More importantly, when over WiFi the program supports full HD (aka HQ) playback, as can be seen above. The program is fast, zippy and even search is pretty solid (though make sure you choose your region and extend the range). Other features include Most Viewed, Most Discussed, Top rated, Categories and History along with thumbnails for each.
Not bad HTC, not bad at all. Combined with their Weather hub update, things are looking better for their app selection.
Update: For those having trouble, try this link for the Zune Marketplace.
Thanks, Charlie S., for the tip!