It's been called "the worst-kept secret in pinball" but the cat is well and truly out of the bag now on Stern's next pinball machine, and it is indeed going to be Avengers (advertisements for "Avengers coming soon from Stern" have shown up in a couple trade magazines this month). It's assumed that the machine is being designed by George Gomez, and as he himself said about some of the whitewoods of his current project, "some of 'em are green..." I'm all the more certain about my prior speculation of this meaning a Hulk Limited Edition version of Avengers pinball.
And while Stern still has made no official announcement or released details beyond "Coming soon", some pinball retailers are already taking pre-orders. The rumor mill has also hinted that this will be a very different design from the typical "fan layout" that Gomez is known for (he is also the designer of Lord of the Rings, one of the most highly regarded modern pinball machines, and definitely an example of the fan layout style).
There's a good chance that more information will come out in the IAAPA (International Association of Amusement Parks and Attractions) show next week (November 13 - 16) in Orlando.