At first glance, the Kelvin would seem to be named for Lord Kelvin. But after watching J. J. Abrams's Ted video, I wonder if it might it be named for his grandfather, Harry Kelvin, who was a profound influence on him.
It is indeed named after Abram's grandfather as stated in an interview on TrekMovie.com in October. Of course the in-universe answer probably has something to do with Lord Kelvin, science, or any number of Scottish thing, much of which were named for something scientific anyway.
I'm sure some supplement writer will craft a whole series of USS Kelvin type ships. Perhaps the USS Système Internationale-class NCC-0501? (laugh) You could see the USS Metre, the USS Ampère, the USS Coulomb, and so on.
Which would be spelt with the American spelling Meter just like the Saber (instead of Sabre) There will be a whole lot of ships appearing with an extra zero before a three digit NCC number...thats gonna drive alot of people a little bit bonkers lol
I also thought it was named for Lord Kelvin, but if it's a way to include a personal reference, that's pretty smart. I wish I have a granddad named like a scientist, too! Ha!