I just realized this while playing TF2. When you die, the camera goes and zooms in on who killed you. In the case of TF2, it even freezes the action. This can be funny and all, but it also has a big negative. Namely, finding a good position to kill from becomes next to impossible.
This is especially true for setting up sentries as engineer. You think you've found a good spot to stick your sentry, where players will be caught in its fire before they know where it is. That works for...oh, the first person your sentry kills. After that either he tells his entire team EXACTLY where you've placed that turret so they can avoid or destroy it, or he simply comes back and destroys it himself.
Same goes for snipers or anyone looking to get the drop on people. You are punished for finding a good spot, nothing is hidden. I head CoD4 multi also has such kill cams. Well, there goes hiding. I guess the reasoning is to cut down on camping...maybe its an issue in some games, but it certainly isnt in TF2. The maps are too small and brightly lit, not very many places to camp. Figuring out where people were was part of the challenge.
Also, while I'm bitching...spys should have a limited number of sappers and shouldnt be able to put them on things as fast as they can click.