Although Skyrim's first DLC, Dawnguard, hit the Xbox 360 in June and the PC in early August, PS3 users are still without even a tentative release date. As the weeks have worn on, PS3 gamers have become increasingly disgruntled with the poor communication and handling of the situation by Bethesda (Skyrim's developer).
Following the announcement
that Hearthfire will be released on the 360 September 4th, tempers flared as PS3 users flocked to leave angry remarks
regarding the situation on Bethesda's blog and forums. Following the quickly increasing amount of consumer backlash, Peter Hines of Bethesda released a statement
We are working on multiple projects, even beyond those two things [Dawnguard/Hearthfire]. We're disappointed too, but we're keeping at it. I continue to do my best to get info and something to update folks with. When I get something I can share, I will.
Microsoft's exclusivity agreement with Bethesda guarantees a one-month early-release on the 360 for Skyrim's first two DLC packs. Dawnguard's exclusivity ended July 26th, and Hearthfire's will end October 4th. Should more DLC be released, Bethesda will be legally able (though not obligated) to release it concurrently on all systems.