First you have take a snapshot of your UV map in the UV editor. Just make sure your map is within the upper right quadrant, otherwise when you take a snapshot I don't think you'll see anything. Once you take the snapshot, a dialog box will open which will allow you to select the destination and file type, among other things. Then, just open up that file in Photoshop. I don't have photoshop yet so that's as far as I can take you.
Hope this helps you out
Don't be satisfied with what you can do but rather strive to do the things you can't do!