I released my first version of sys-cpu today. It only supports solaris at the moment, and doesn't have all the functionality I'd like it to have, but there it is. Release early, release often.
I tried getting at the cpu temperature via a file called "envctrl_gen.h", which I was led to by hfb's earlier comments. Unfortunately, my attempts to merely #include this file causes the compiler to complain loudly, so I'm not sure if I'm doing something wrong or if the file itself is busted.
Anyway, I think I'll work on the Linux version this weekend.
Update: ok, I didn't have my -I line set correctly. Now I can get a cpu temp....of 66784. Hmm....time to figure out the conversion.