OK, I only asked if you were sure it was the steering because low transmission fluid makes a similar noise.
As far as the rack leaking, they are actually quite common on the "W" cars (LaCrosse & Grand Prix). They leak inside the bellows and they leak at the bearing adjuster, I've never seen on '08 start leaking yet, but its the same as previous years, so I'm sure it was only a matter of time.
I asked about the fluid, because some vehicles are prone to steering noise from the pump, and GM has been having dealers put Valvoline Synthetic fluid in the system. So flushing it was the right call, we just don't know what fluid was put back in.
Also, because of the frequency of noises, GM also came out with a new bleeding tool (which every dealer should have been sent one). Its important to also use that tool.
I don't think your being scammed about the rack. As long as they don't try and charge you, then let them do what they think needs done. The scam is when they never fix it, and then try and charge you once its out of warranty. So take it back!!!!