I just picked the game up from wal mart sealed 4 days ago just beat it.It includes one time use code for the network that comes with 5 free downloadable items and missions and a very nice armor suit.the code says it expires jan 2012 but it still worked for me
When I got the non platinum version it had the Cerberus Network, which included a few things (normandy crash site, zaeed, cerberus weapon and armor, arc projector, firewalker pack). So, it sounds like the Platinum hits version doesn't include the full DLC.
The main ones I'd like to get are Shadow Broker, Kasumi, Overlord and Arrival. Seems a little silly to have to pay $31 for a few DLC, when the full game is < $20. Wish there was a way to get all 4 for $5-10.