I started playing Go again recently after a few years off. I was initially disappointed in my strength - my KGS rank stabilized at 21k or so, and I remember working hard toward 12k when I stopped, so that's about 8 or 9 stones lost.
Over the weekend, I installed GnuGo on my PC, and let it beat me four games straight. I got on
www.goproblems.com and ground my way through some exercises. I drank a raw egg, and punched bowls of hot ball bearings. The important thing is, though, I got enough Go in a short enough time that my brain went into "learn Go" mode, and I started seeing the stones every time I closed my eyes. This is a sure sign my brain is reprogramming itself to recognize a new kind of pattern.
I then got back on KGS, and played a 13k go-bot with a 4 stone handicap, and won by more than 30 points. I also played a 22k human, giving him 4 stones, and won by resignation (he was at least 60 points down). I'm just at 17k, it seems. I'll have to do some more even games against humans to know how strong I really am for sure - handicap games are a bit wierd. Black (who always gets the benefit of the handicap, and is presumably the weaker player) goes defensive, and white has to overplay in a way that won't work against someone of equal or greater rank to make points.
According to the guys on KGS, there is a Korean go server called dashn which is known for producing crazy-strong fighters in the 15k-5k range. The dashn-trained players are said to deviate from the joseki in ways that lead to complicated, sprawling fights. A player has to be pretty damned strong to know the joseki well enough to punish this. I might have to play a few months over there to get what benefit that might provide.