I have had this problem for the last few iterations of Photoshop, but I can't remember when it started. I am surprised that I haven't seen anyone else mention it.
When I move the screen (for instance, when at 100% on a large document) using flicks on my Magic Mouse (Mac OS, of course), the screen will continue scrolling for 10-15 or more seconds after my last flick. This means that it is basically impossible to scroll using flicks on the mouse. I find using the space bar + drag much less intuitive and much slower, and since I can barely see the scroll bars in the modern Mac user interface, I am spending way too much time doing things that used to be dead simple.