I initially thought I got burned when I bought Monty Python and the Holy Grail and, literally two weeks later, the SE comes out. Pissed me off until I discovered there's virtually no difference.
I am about to be burned by Casablanca, though. That was one of my first DVDs and now a 2 disc set is going to be coming out with deleted scenes (not spliced back in to the best of my knowledge). I was just about to buy Scarface also until I found out late last week that it's being rereleased in November in a 2 disc set. The same goes for The Seven Samurai which I was about to buy until I found out Criterion is rereleasing it. Maybe it'll actually be cheaper (sheeyah, right, and monkeys might fly out of my butt).