Search results are formatted specifically for the iPhone's screen, so you no longer have to scroll from side-to-side. Local search results now include easier-to-press "Get Directions" and "Click-to-Call" links.
When there's single or multiple listing that is accessible using the "Show Map" link, the map pops up by default.
If you prefer the classic desktop search results format, tap the 'Classic" link near the bottom of each page and everything will be the same as it ever was.
For now, the newly formatted results pages are available only in U.S. English and for iPhone and iPod Touch firmware version 2.x. The two mobile team engineers say Google intends to make the newly formatted results pages available on the iPhone and other devices and in more languages and countries. They don't say when that will happen, however.