Hi,
from swissair times I actually got upgraded a couple of times, at baggage check-in in Montreal I asked if there was anyway to get a C class ticket and the lady replied "you are already in business sir". The only time I have actually gotten upgraded at the gate was in Dubai with Emirates, otherwise some other times when I was directly put into business. The fact is on the two occasions with swissair I was flying on to Geneva, (SFO-ZRH-GVA, YUL-ZRH-GVA) and both times for the zrh-gva i was put in economy. May I add that I have always been a normal qualiflyer member. The other day flying to EZE i saw a lot of operational upgrades being done at the gate, where people were called and given new boarding cards (they had Y than passed to C) I think this was done to about 20 people.

hope it helps.