Yes, I'm still working at Gearbox (going on 8 years now).
I'm glad you like Borderlands. I think many people here were surprised at how well it has done. We weren't sure if many people would like it.
I'm currently working on the Aliens: Colonial Marines game. I haven't done much AI stuff since the Brothers in Arms games (where I and one other guy did much of the AI code for it). I'm doing just about everything else now (weapon code, animation code, audio code, level editor coding, rendering stuff, physics stuff, networking stuff, etc.).
I wasn't sure if any of the "old timers" were still posting here or not. I guess the Half-Life community has pretty much moved on to TF2 and Left 4 Dead. I saw something a while back about a Valve bot going to be released for TF2 (based on the bot from Counter-Strike and Left 4 Dead) but I never saw whether anything was released or not.
Anyway, I hope everyone here is still experimenting with bot coding and having fun.
I'll try to check back from time to time.