Take a look at the two Safari screens above. The one on the left is from the upcoming iPhone OS 4.0; on the right, OS 3.x. Notice anything different?
Yep, the "Search" button. In 3.x, it's branded as "Google." 4.0: a generic "Search."
What gives? Well, there are rumors that Apple wants to move away from Google and is in discussions with Bing to make them the default search engine on iDevices. (You would still be able to "iGoogle," though, as a user-selectable option.)
It can also be seen as the latest broadside in the Apple vs. Google war, which has included Uncle Steve publicly bashing the Nexus One as Google's attempts to slay the iPhone and both companies snapping up mobile advertising providers in an attempt to get some of those handheld ad-impression click throughs.