[robg adds: As you can also press the home button once from any screen to get back to the Home screen, you can quickly reach search from any screen by tapping the home button, waiting a small amount of time, then tapping it again.
This feature is documented in the new version of Apple's iPhone User Guide (11MB PDF), but as I know that's not necessarily widely read, I thought I'd go ahead and run this one. I may do similar things with other documented 3.0 features if they haven't been widely discussed. ]

