Finding the Google Street View feature in the iPhone 2.2 version of Maps is tricky - there's no button for it. If you're viewing a map that you think might have a street view, drop a pin (tap the curled paper icon at lower right, then tap Drop Pin or Replace Pin if a pin is already being used). An orange person icon at the left of the pin's information line is dark and can be tapped if Street View information is available.

From Glenn Fleishman