Bungie has recently announced on their community blog that they have entered into a 10-year publishing agreement with Activision. From what is mentioned in the announcement, it appears this new partnership is meant to allow Bungie a world-wide recognized publisher with which to release original intellectual property on mulitple platforms:
The groundbreaking alliance will provide Bungie its first such partnership since splitting off from Microsoft in 2007, significantly broadening its global reach by providing the resources and support to develop, distribute and release games worldwide on multiple platforms and devices.
The details of the agreement stipulate that Activision retains the right to publish Bungie games based on new, original IP's which can translate to "no halo on PS3" depending on how you look at it. Bungie also retains all rights to their own content and will remain an independent company from Activision, meaning the possibility of another Infinity Ward/Activision fiasco would be highly unlikely.
It'll be interesting to see what kind of plans Bungie has with this new agreement. With E3 little more than a month away we expect more details to come to light. Stay tuned for more information as it develops.