They're not meaningful at all. Hopefully relatively few people really think I'm one of the "top 15 living programmers" or anything like that.

I'm good enough to make a living, and good enough to help people on SO. One of the nice things about programming is that what you find interesting, I might not and vice versa - hopefully there will always be enough people who find a variety of topics interesting to hope those who have problems in those topics. But yes, considering rep as a proxy metric for programming awesomeness would be a mistake IMO.