It would affect your tires more than anything I would think. You'll likely find bad vibration at certain speeds. As far as brakes go, 850 brakes are pretty finicky, but I can't see a direct problem with the brakes with a bent rim. The rotor should still be true.
If they are bent somewhat severly then i would like to know how your tires are holding air. If they are not severe enough to effect them holding air, then I would say its not a real bad problem, but its not good either. It will effect handeling some, tire wear, and can cause the car to "pulsate" at constant highway speeds. I dont know if Pulsate was a good word for it, but I cant think of a better one, I had two bent wheels in the front and they caused the car to sound like the wheels were not balanced, it also caused the car to vibrate some at these highway speeds.
i've got two bent volans...i use the more bent one for spare. the less bent one isn't really noticable...but air does slowly leak out ...maybe 1 psi per month or something, while the other 3 normal rims keep air relatively well. just becareful the air doesn't get too low