Marvel has released an image of an Avengers story arc in December. We're not sure if it's just a story arc for the regular books or an actual event. The details (including the creative team behind this) will be revealed Tuesday, September 13 at 2pm central time.
Speculation is that it may have something to do with the X-Men as well since the target sight doesn't make a cross but rather an X. Plus it's on record that 2012 is the year of the X-Men. Hmmm... we shall see.