Google released a standalone version of its YouTube app for iOS users today. YouTube is included in iOS 5, but the latest beta version of iOS 6 removes the popular video player. With iOS 6 expected to be released in the next few weeks, iPhone owners will be able to download the YouTube app to their phone.
The YouTube app includes voice search, a channel guide and a social network support. The current version of the app is compatible with the iPhone, but I would expect to see an iPad version soon. It is available for free in the iOS App Store.