The pad doesn't have to be a touchscreen size to take advantage of the gestures.
Already I use the alternate click and the scrolling one quite often on my wife's MB. Her trackpad is a reasonable size to work in. It's almost a tad bit bigger than my palm treo screen and a tad bit smaller and an iphone/ipod touch screen (by tad I'm not talking 1/16" yes we all know it's smaller than those 2 devices) but it's well within reasonable size to use over half the gestures.
Look at it this way. They put the update out people b!tch about the size of the trackpad, they don't put the update out people b!tch about not having it. The solution? Take their MBX's away and send them to bed with no diner.
I prefer they send it out and give us the OPTION to enable them or not. If our trackpads support it, I think having the choice of using them is better than not having the choice at all.