With every successive iPhone SDK release, developers have been uncovering more and more clues about what new features will be included with iPhone 2.0. The fifth iPhone SDK release has kicked off another round of digging for changes, and has brought two new features to light.

News of better YouTube integration in Safari comes from the Boy Genius Report. The new integration modifies Safari to display YouTube videos on web pages as links. Click on the link and the video will open in the native YouTube application. You can also return to the page very easily once you've finished viewing the clip. Unfortunately, we still don't have a real Flash Player implementation for the iPhone, so the actual YouTube site remains off-limits.

A TUAW reader tip provides information on the second new feature, which is support for .Mac push e-mail. The .Mac service has offered push e-mail functionality to its users for a while now, but the iPhone has been a bit slow to the party. However, the latest firmware includes a setting for turning push e-mail for .Mac on, and several developers who are currently in the beta program have chimed in in the comments section to say that the feature works quite well. Let's hope Apple adds syncing for the other .Mac features, as well.