I have since December 2009 an Android cell phone.
AdSense shows up just like on a normal computer.
The screen is 480x320, but I can zoom, that my 600 pixel width content is all at once on the 480 width.
I use my Android regular for browsing when I am not at home.
I did not use my cell phone before with 240x320 screen and unuseable browser.
So I think Android and iPhone users can see my pages as is with AdSense, the rest is not interesting for my sort of visitors.