Google decided to not wait until the release of iOS 6 to introduce a stand-alone YouTube app for the iPhone. It's available now.
When the first iPhone was introduced, Apple and Google were united in competition with Microsoft. That's why some of the standard features of the iOS were tied to Google services.
Five years later, these two are bitter rivals, with Apple's iOS and Google's Android OS battling for the top spot in the smartphone, and Microsoft trailing well behind. Apple is now pulling the ties to it's chief rival's services out of its operating system.
As a result, iOS 6 won't come with the YouTube app that has been bundled with its device since iOS 1. This means that Google had to release its own, which it has now done.
There is at least one advantage to this: the stand-alone app can display more videos because it supports in-video ads. Also, Google will be able to update this software at any time, not just when new versions of the iOS are released.
This app is free and can be found in the iTunes App Store. It currently fully supports only the iPhone. iPad users will have to wait for full support.