Another lens to consider is the 200mm f/2.8 L if you can do without the zoom on your long lens. It is as good as the 70-200 IS2 long end, very light weight and compact comparitively speaking, mint used for about $500. I actually have both of these lenses...bought the 70-200 IS2 new and bought a mint 200 f/2.8 for $460. It's very difficult to tell them apart when doing comparison shots.
Nice thing is it would get you into a very good longer lens for not much $ if you buy used and you can always turn it for what you paid if/when you want to go for the 70-200 IS2.
The 70-200 IS2 is a fantastic lens but that thing is a boat anchor, so there is a certain desireableness to the compactness and light weight of the 200 f/2.8 that keeps it around here despite the redundancy "shot-wise", especially given not much $ tied up in it.