I don't think someone should be made a Sir or Dame (or any of the other awards) just because they won a gold medal at the Olympics. These awards should be for a lifetime of achievement and service not just something you do in one year.
With the emphasis on *service*. Note that most popular entertainers don't get honours for, say, selling millions of records, cinema tickets etc. - that's how they make their money, and is inherently selfish, as it benefits them: they get honours for services to charities, good works and so on. Equally, being successful in your chosen career is what you get paid for: you aren't awarded honours for running X 100 m races in the IAAF calendar or Y grand slams, any more than I'd be awarded one for, say, clocking up 20 million words written, or something - good grief, if Roger Federer were British I wouldn't be recommending that he be knighted, even with *17* GS. Olympic medals are perhaps a different matter, because you are winning something for your country, but you need to do a lot more than win just one to merit a knighthood. As it is, I'm surprised that Murray (and others) have skipped the MBE stage (I don't think a lot of previous medallists did) and gone straight to OBE, but I'll put that down to the Government trying to inflate the importance of the honours being awarded.
And I definitely think that knighthoods (and damehoods, or whatever the word is) should be reserved for those who are the end of their careers, or close to it. They should crown a "life" of achievement in a sport, not be awarded at the first serious success. Consequently, I'm a little uncomfortable with Chris Hoy having been awarded one while he was still racing, irrespective of his achievements.