The very first Brink DLC is on the way, only slightly later than originally anticipated. When first announced, the "Agents of Change" content was set for June, but now Brink players can expect to get their free goods in early July. "Agents of Change" will bring in two new maps, weapons attachments, outfits, and a number of new abilities to play around with.
Note that the DLC won't stay free for too long. If you're keen on getting these for free, you'll have to download the content pack within the first two weeks of its release, whether on Xbox LIVE, PSN, or PC.