If this analyst is right, I am willing to bet the iPhone will be Gphone enabled:

But Richard Doherty, research director at The Envisioneering Group, says Google is driving toward getting device makers to produce basic handsets equipped with a “Gbutton” that takes users right to a Google texting screen. The goal: Get GPhone texters in the habit of querying its vast databases for directions, phone numbers, movie times or restaurant tips and woo advertisers to sponsor GPhone-delivered answers, Doherty says.  Link—>

This makes a lot of sense for both parties and creates yet another potential revenue stream for the iPhone  as the software approach will likely involve revenue sharing, just like a Google toolbar does.  Given the integration with YouTube already present on the iPhone, I wouldn’t be surprised to see the Google phone software get coveted icon placement on the iPhone as well.