Right now I have my late 2011 15" MBP hooked up to an external display running iTunes and browsing the web and i'm at 148 degrees F on the CPU and about 130 Heat Sink according to istat.
The funny think is I had a Speck Snap on case installed when I noticed the temp. I took it off after reading about heat build up caused by the case and noticed that it made no difference without it. Funny huh? I'll put the case back on and stop worrying.