I have an 07 550 with about 7,000 miles, I've noticed since I've purchased it that it always squeaks when coming to a rolling stop...I took it to the dealer and all they fed me was some BS about it being brake dust built up. Anyone have any thoughts?

You’re entitled to free replacement pads and/or rotors if needed for the first 12 months / 12,000 miles. If the dealer refuses, ask to have your area MBUSA Service Parts and Operations Manager (SPOM) intervene.

do what he said, but mercedes is infamous for squeeky brakes

Can depend on driving style. Jump on the brakes more agressively and see what happens. My '06 CLS500 had no problems, and my '07 CLS550 with 1,200 miles, no problems.
I read on the web about how when you first put pads in you need to make moderate stops to bed the pads. I never had the guts to do it but the literature is there.

http://www.se-r.net/brakes/breakin.html

i have had trouble with my 05 e500 since about 12000 miles. I currently have 48000 miles and have changed the front pads at 25,000 miles and the rear pads at 42,000 miles. Each time the dealer replaced it and I came away frustrated at the lack of concern that I was experiencing severe squeaking everytime I would brake at low speeds. Replacing the pads did help for a few thousand miles but sure enough I have been driving around with the squeaks again. So frustrating. The advisors are worthless. I am thinking of replacing my front pads again with a ceramic pad, some of the posts here seem to suggest a less dusty pad will help. Not sure. If anyone has any similar experience please post and maybe some solutions. The squeaking is enough to make me want to sell my car and lease a new cls but not after reading your post.