Apple has confirmed what everyone was expecting: that content from the fourth most visited site the in the world will stream through AT&T’s wireless network directly on your craved iPhone.

Apple has built an application specifically for YouTube’s original content, which will stream through Wi-Fi or EDGE networks.

In addition, Apple announced that YouTube is now live on Apple TV™. Users can download the free software update using Apple TV’s built-in software update feature, and then easily navigate through YouTube’s familiar video browsing categories or search for specific videos. YouTube members can also log-in to their YouTube accounts on Apple TV to view and save their favorite videos.

“iPhone delivers the best YouTube mobile experience by far,” said Steve Jobs, Apple’s CEO. “Now users can enjoy YouTube wherever they are—on their iPhone, on their Mac or on a widescreen TV in their living room with Apple TV.”

Just as Joost and Babelgum (the two Internet start-ups that deliver quality TV signal through peer-to-peer technology), YouTube has also started to encode uploaded videos using CoreCodec’s H.264 codec. The iPhone thus becomes the first mobile device that streams YouTube’s H.264-encoded content. Moreover, the encoding allows for longer battery life and improves video quality.

Over 10,000 videos will be available on June 29, and YouTube will be adding more each week until their full catalog of videos is available in the H.264 format this fall.

The application that helps stream YouTube’s content will be pre-installed on every iPhone, when the phone debuts on June 29.