Originally Posted by Ham Salad 360
Also, I picked up a copy of Portal 2 for the 360 that has a Platinum Hits sticker and a notice that it includes the Peer Review DLC. While this sounds as if it is included on the disc, it actually isn't, and there is an insert in the case directing you to download the DLC from the marketplace.
You also might want to add the Platinum Hits version of Left 4 Dead for the 360, which includes the Survival DLC (which was free), but none of the other, paid DLC. (Although, I just realized that Valve might've handled this like they did Portal 2, and not actually included it on the disc.)
Peer Review DLC is free for everyone.
Edit: The reason why Mass Effect 1 had a GOTY edition and Mass Effect 2 for the PC/XBox 360 still do not is because of EA. Newegg has a copy of Platinum Hits Mass Effect 1