Multitouch has passed Windows Mobile by, mainly on account of the fact that 6.1 doesn't support capacitive screens—the kind needed for multi-finger gestures to register. Even if it did, the OS is far from multitouch-ready.
With the Leo, it looks like HTC's pulled another Hero: They've taken an OS that isn't designed for multitouch out of the box—in this case Windows Mobile 6.5 instead of Android—and added gestures to specific applications themselves: in this case the browser, Google Maps, the photo viewer and the video app. But where else would you want it, honestly?
Best of all, the Leo's 1GHz Snapdragon processor renders pinch zooming waaaay more smoothly than the Hero's dumpier processor, also from Qualcomm, handling multitouch video gestures without a hint of stuttering.