FWIW, I read a Time article about centernarians in the summer of 2003 (I believe), and they made the point that there are 70,000 centernarians in America and it is the fastest growing demographic. If you can find it anywhere, it's a really interesting read.
The best quote from there was (paraphrasing):
"Most people think 'the older you get, the sicker you get'. But for centernarians, it's 'the older you get, the healthier you've been'".
Also, I've read the stats on the Okinawins and they have the same "high risk" and "low risk" genes that Americans have.
Doesn't add much to the conversation (I rarely do...)