YouTube just rolled out a new version of their mobile site at m.youtube.com featuring an arguable better interface and higher quality video playback than what's offered in the iPhone's native YouTube application.
Putting aside the drama of Google releasing this as an in-your-face move to Apple (iOS devices all have a native YouTube app built in that lacks a lot of the features you can get in the new mobile version, and the new mobile site actively prompts you to add it as a home screen bookmark), the new mobile YouTube site works on both iPhone and Android devices and is a nice step forward for mobile browsers supporting HTML5.
Nice features you can now get from the mobile site (that you can't get from the native iPhone application) include auto-suggest search results and playlist creation. More importantly, though, web apps can iteratively upgrade in small doses at any time, so YouTube's main access point (the site) remains universal across devices and consistent with the desktop site. (As TechCrunch notes, the iPhone app still uses YouTube's out-of-commission five-star rating system rather than their new Like/Dislike judgments.)
YouTube's currently rolling out the update across its servers. I was able to access it right away, but other writers at Lifehacker weren't, so your mileage may vary. In a few days, it should be available to everyone.
YouTube Mobile gets a kick start [Official YouTube Blog]