Google has unbundled another part of Android from the OS itself, and has put a new version of YouTube, 2.1, into the Android Market. The company earlier said it was going to continue to do this, so that important but not central portions of platform functionality no longer need be tied to Android OS releases.
In this case, the bad news is that the new version of YouTube requires Froyo (Android 2.2) on your device. The good news lies in the changes. In addition to saying that the YouTube app was rebuilt from the ground up to mirror the desktop experience, Google also said thew new version is their "fastest, most intuitive YouTube mobile app to date." In addition:
In-page playback: you can read the video description, browse related, rate or flag videos without having to interrupt video playback.
Posting comments: you can post a comment while the video is playing, just like on the desktop website.
Subscription updates: we've made it easier to access new videos from your subscriptions. If you are signed into your account, you will see all your subscription updates right on the home screen of the app.
New full-screen UI: To enter full-screen mode simply rotate the phone. The new player controls make it easier to seek within the video, and you can pause or resume the playback by just tapping on the screen.
Google took feedback on the earlier version of the unbundled YouTube from a few of weeks back, and included some of those suggestions in version 2.1. In addition to being in the Android Market, as 2.3 rolls out (it will be on the upcoming Nexus S, for once), that platform version also has YouTube 2.1 pre-installed.