magic-trackpadtrackpad
Why don't older Macbooks (Macbooks with a physical button on them, I think up until 2008) support multi-touch when upgraded to an operating system that supports it?
They are able to distinguish two fingers opposed to one for scrolling and secondary click along with also being able to identify more than 2 fingers. Is there a hardware limitation of some sort, or is it just restricted for some other reason?
The trackpad in the 2008 white plastic MacBook isn't capable of supporting multitouch gestures. As it's a hardware limitation -- meaning the trackpad hardware can't sense input from 3-4 separate fingers at once -- there aren't any hacks to get around the limitation.
One way to get full multitouch support would be to get a Magic Trackpad. They'll work with any bluetooth-enabled Mac running Mac OS X Snow Leopard v10.6.4 or later.
BetterTouchTool lets you create custom gestures, with custom actions. There are a variety of single-finger gestures:
Have a look at it, and see if it suits your need.
Best Answer
Hardware limitations. Note that Mountain Lion's supported models are for at least partially multitouch-capable trackpads; ML doesn't require you to use, say, a 4-finger swipe.
I haven't used any of my Magic Trackpads with 10.8 yet, but it should be fine.