I think it is completely normal but I just got my MacBook yesterday as a replacement. I must say it is pretty good but the damn fan IS ALWAYS ON!! It has not stopped in the past 2 hours and I only have Audium and Safari open. The temps for the CPU is from 130*-175*F. I think it is normal but the fan is loud and annoying.
Mine stays at around 50c after a few hours use with it on my lap. Not sure if that's normal or not. I'm not doing anything taxing, just MR and adium. It's not uncomfortably hot, but I was expecting it to stay atound 40-45c.