Here's a video that illustrates the multi-touch capabilities of the HTC Touch Diamond and Touch Pro phones. This is not part of the feature list of these phones but according to Engadget it's present in HTC's own debug application.
While multi-touch input might be all the rage in handhelds and laptop trackpads at the moment, alas, it's not on the feature list for HTC's latest Touch Diamond and Touch Pro. However, the capability is indeed present and exploited on video by HTC's own debug application. Even more interesting is the way that the handsets' entire front, capacitive surface (not just the 2.8-inch, 640 x 480 pixel display) can be used for multi-finger input.