I kinda/sorta mentioned this in my Picture Problems thread too, but you beat me to it. I just joked that I tried rubbing my eyes, but it didn't help. :p
Anyway, I could go either way. 80x80 was fine by me, and 100x100 is ok, but I figure most won't bother re-editing their avatars and will leave them blurry. And we can't change them for now anyway.