I performed my first sensor cleaning on my 20D today, somewhat overdue (I've been changing lenses outside a lot recently, and it showed badly). I ended up having to do it twice, once with a large brush and once with a small brush. I think I still missed a fleck in one corner, but it's absolutely tiny, and I can ignore it until more junk accumulates.

It was, in a way, an absolutely terrifying experience. Screw this procedure up bad enough and you've just disabled or destroyed a thousand dollar camera. My nerves were not helped by the visibility of a thinly streaked sheen visible on the sensor in sunlight. At some point, I may do a liquid-based clean, but not now. Like everything else that tends to affect me this way, it only started catching up to me when I was doing the testing. Actually performing the cleaning bothered me not at all.

Test shots taken after my second cleaning showed a drastic improvement, and no signs of damage, though I gave myself another start when I forgot to reset from ISO 800 (I thought I had been shooting), and was startled by the noise. Another few test shots at ISO 100 came out fine.

I'll probably feel better about the process the next time I have to perform it. After a while, I'm sure it will become routine. The first time is always rough, though, when you have no guidance or hand-holding other than your own research on the internet.