Friday I gave another iteration of our free Sucessful Technical Speaking class, upgraded some since the last version, and this was my first time using the Presenter View in 2007. If you haven't seen it yet here is a page about it from MS, but basically it makes it very easy to show the audience the slides while you see a smaller version of the current slide, your notes in an expanded pane, and an easy to navigate list of slide images below that. Only time I had a problem with it was when I wanted to switch from Powerpoint to something else, had to work to get that view up on the right monitor - but that might be me learning how it works still. As far as presenting it's entirely usable and for the first time makes it easy to use notes embedded in the deck.
Here's a list of New Stuff in Powerpoint 2007 you might find interesting as well.