The sound definately seems to originate from around the brake pedal itself. The engine does not run rough when i hear the hissing noise.

In fact, the engine doesn't have to be on at all. Nor does the car have to be moving. I can just hop in my parked car, depress the brake to that certain point and I get the continuous hissing noise until I move off that point.

Will check resevoir to see if I'm losing fluid in the morning!

Thanks for the help, guys!!!!