I had just recently started looking into this. I agree, and suppose that anything is possible in the right conditions. There are a number of videos on youtube of people claiming to be reaching 500 yards. Those videos seem questionable though. These two videos below are the first ones I found that really impressed me. The guy with the pistol has some seriously steady hands!
PISTOL SNIPER (22 LR @ 400 YARDS)(Ruger MKIII/22/45) :
http://www.youtube.com/watch?v=EyjQESIp9wk
.22 Long Rifle 400 YARDS!!! (10/22):
http://www.youtube.com/watch?v=1jylb...eature=related