Thanks for the detailed response EZ Jim,
Yes, turns out after I posted this, I was reading through the Logitech Support pages, and found a similar answer in that no drivers should be required since Mac OS X has UVC drivers included as of 10.4.8 onward (great idea on Apple's part!) — with that information I decided to take a chance, and purchased a Logitech c270 for about $50AU.
So far I've tested it with a number of applications, I figured I'd try Photo Booth first, it works well.
I then tried to set up iChat with my iCloud account, couldn't seem to get that to work, so I called Apple Support, who helped me find the FaceTime app for Snow Leopard, got my iCloud account connected and was able to make a successful call to a family member. (I found the picture quality very nice for a small 720p camera.)
I also figured that since the webcam has a microphone built in, I'd also try using it for audio recording, it worked, which is handy meaning I won't have to connect an external microphone through the line-in.
I've still got a few uses I want to test it with such as Yahoo Messenger and Skype, but I'm confident that given my success so far it will work just fine. :)