I've flown on my birthday at least a half-dozen times and have never been upgraded, despite looking friendly and otherwise "upgradeable." of course, I always print BPs from the kiosks, so maybe it's just the machinery that doesn't care about me.

I've stood behind people at check-in counters who were trying to score free upgrades due to birthdays, pregnancies, and job offers. The pregnancy couple scored the upgrade, the others did not.

I must say, I find it appalling that a 10-week old fetus gets upgraded before a (then) UA 1p!!