Multi-touch for the iPhone OS Google Earth app is undisputedly cool. That said, how often do I use that app? Not since the day I installed it. As I've mentioned before, multi-touch is not needed for zooming/unzooming in mobile Safari 99.99% of the time. The iPhone OS webkit double-tap/zoom-to-the-div-width feature (WebTap?) practically eliminates the need for multi-touch. So, in general, how often do I use multi-touch? .01% of the time. YMMV*, blah, blah blah, blah blah.

*May increase risk of heart attack or may cause anal leakage.