In my quest to get cpu info on solaris, I came across the command "prtdiag". Most solaris boxes have it (I think), though it's probably not in your path. Check/usr/platform/<system>/sbin, where <system> is the current system type (probably "sun4u" these days, but double check).
Anyway, it provides a lot more information than ye ol' sys/processor.h file does, including cpu temperature and exact type, plus some other goodies. I'm now searching for the source for prtdiag to see if I can wrap it.:)