Step 1: Place iPhone on table
Step 2: Grab digital camera
Step 3: Take picture using digital camera of said iPhone
Now you have your screenshot!
Seriously though, I don't think there is a way to do this on the iPhone.... yet.....
Hold [HOME] and press the [OFF/LOCK] button
saves to ur Camera Library as .png's
To take a screen grab on your iPhone with Software 2.0, just hold down the home button, then tap the top button. Your screen will flash white signifying you have captured your screen.