I travel the globe and have done for many years doing presentations on projectors whereever I need to. Always, plugging my MAC into ANY projector I come across for my presentation would result in an instant "hey presto" - it works always, first time and every time and at a decent resolution too when applicable.
However, for the last 4 months or so (since the last update LION I think), I have noticed, plugging in a projector results in a hit or miss experience. In the just the last 10 days, I have only got the project to work first time 3 out of 10 times! In fact, on 4 occasions only a reboot of the MAC would result in the projector being detected allowing the correct resolution. On both a HP and Epsom (pretty standard and always work), the last flaw was, it would not let me chance the resolution beyoind 800x600. I looked up each projector on line and it was obvious they could both go much higher. After a reboot of the MAC (ouch, sounds like Microsoft), the projector allowed to me correct set the even as high as 1440... as per the projector spec.
So, what gives, I did some research and see others with similar problems. Bear in mind you sometimes get a few minutes when you walk into a meeting / conference room to setup and present. This does not BODE well and a lot of people laugh at the "flawless" MAC now acting like a PC. Very embaressing!!!
My MACBOOK Pro is just under one year old and I use the Thunderbolt->VGA adapter with nothing else in it. I know it's not the cable because after the reboot, it just works!!