I'd say 83C under full load is too hot, although that kind of peak temp seems to be the norm for MBPs, currently.
If I'm not mistaken, pre MBP laptops have an absolute max temp of around 74C at which point the computer will automatically shut down.PB
I've just used your script to run my Powerbook at 100% CPU, and at an ambient room temp of 20C my PB's processor reached 59.5C, at which point the left fan activated bringing the processor temp back down to 55C, when the fan then deactivated. When maintaining a continuous 100% CPU, my PB's processor stayed within the 55.9C-55C range, fan always cutting in at 59.5C and cutting out at 55C. At idle, my PB is currently maintaining a processor temp of 40.3C.
In the past, I've noticed when my PB was doing something processor intensive for an extended period in an ambient temp environment of around 30C (during a hot summer), my PB's temp would stay in the low 60s, with the left fan constantly running. My PB's right fan, which, I believe, is supposed to activate only if the processor reaches a critical temp (74C?), has never, yet, cut in, but then the internal PB temp has never gotten anywhere near that high.
I have to mention, here, that I ALWAYS run my PB on a raised cooling platform (Podium Cool Pad:
http://roadtools.com/), and during hot weather, have an electric fan blowing air on both me and my PB.
I would think that MBPs regularly reaching temps of 83C would eventually have problems due to the excessive heat. It just can't be healthy for the MBP's guts.
I hope Apple finds a way to enable MBPs to run cooler. I eventually want to get one, but not before the heat issue is resolved.