Last night I test drove the idea of using the iPad as a digital music stand. I arrange music for and play in the Emerald City Jazz Orchestra in Seattle WA. So I created PDFs of the music, copied them to the iPad, and used GoodReader to view them on our monthly gig last night.
Since the iPad is a little smaller than a standard sheet of 8.5" x 11" paper, I expected to have some trouble reading the parts. We also use old-style "sax fronts" for music stands, which put the reading area further from your eyes. However, the bright, crisp display made that job easier.
When the gig started, I hadn't thought to turn off the automatic sleep function, so I had to remind myself to tap the screen every once in awhile to reset the timer. Page turns were a minor problem - when you have both hands on a baritone saxophone, you don't have a free finger to tap the screen! There are page layout workarounds for that which I didn't try for this test.
Generally, GoodReader was easy enough to use for this purpose, although I never seemed to get the number of taps right when trying to bring the controls back onscreen (I believe it's three-fingers, double-tap).
I think the iPad can work as a digital music stand if you can get it closer to your eyes. Next time I'll use a standard-height music stand and see if that makes a difference. I've also seen that RAM Mounts is coming out with an iPad holder. If there's a clamp that can mount to a standard mike stand, then you'd have a great setup. Might take some more research!