In reply to Chloe:
It isn't easy and the results depend to some extent on the route---straight up and down pitches offer little more than butt-shots of the leader, for instance. Traversing or diagonaling routes are much more likely to yield decent photos. Here are some things that have worked for me.
Both climbers should have small point-and-shoots, carried in a way that makes them instantly accessible and releasable. A second chalk bag for the camera is one carrying possibility that has worked well for one of my partners. I have a very small fitted LowePro case that I carry around my waist like a chalkbag. You want to be able to spin the camera out of the way when you are climbing but be able to get at it at a moment's notice.
As for releasability, a retractable tether is one possibility: see for example
http://gearkeeperblog.com/2010/08/26/retractable-camera-tether-keeps-camera... . This company makes a case with built-in retractor cord:
http://www.t-reignoutdoor.com/collections/procase . There are retractable tethers for laser rangerfinders that would work well with cameras; eg
http://www.amazon.com/Nikon-8172-Retractable-Rangefinder-Tether/dp/B000JJGY... . There are also coiled-cord models like
http://www.cetaceacorp.com/2-ft-camera-tether-en-2-3.html#.UfiFP6yZa2k%29 , and the Wild Country Pro Key nut tool has a coiled-cord leash that would work. I'm sure googling will turn up a host of other possibilities.
All that said, I've found it pretty simple to just clip the camera to an over-the shoulder sling when getting ready to belay. The clipping tether should be quite short.
As for photographing while belaying, I don't think it is all that dangerous. Obviously, you don't want to be doing it while the leader is sketching in mid-crux, but there are usually multiple times during the climbing of a pitch when a camera could be quickly deployed for a shot. Most---maybe all---point and shoots need to be used right-handed, which is also going to be most people's belay hand. But it isn't hard to momentarily lock off with the left hand and use the right to fire off a shot if your set-up makes it easy to grab and release the camera.
If you are a bare-handed belayer, nothing more need be said, but if you wear gloves (and I think it wise to do so), then you will have a problem with the shutter release. Either fingerless gloves or a hole cut in the index finger of regular belay gloves will be required. There are excellent gloves made for handling rigging on sailboats that expose the tips of the thumb and index finger and cover the remaining fingers.
What matters most is the commitment of both climbers to actually use their cameras, but it helps enormously to have a really good set-up.
You can lug an SLR, and if you want very high quality you have to do that, but that does constitute a substantial encumbrance, and there is a tendency for the big camera to live rather inaccessibly in a pack.
Here's an example of the results of such methods:
http://www.supertopo.com/tr/A-Week-in-Red-Rock-151-A-Photo-Essay/t371n.html . I did have a DSLR along and used it for the scenic shots, but all the climbing pics (and pics on the climbing approaches) were taken with point-and-shoots.
Post edited at 20:34