I have it from a source working inside NASA that the location for Avengers filming will be the John Glenn Space Power Facility in Sandusky, Ohio, just west of Cleveland. This is not confirmed, but I know someone who works at that facility and they are being updated regularly. I will keep my ears open for the CBM fans!
CBM Insert: User Orphix gives us this bit of added information which may be the reason for this location--a massive vaccum chamber...
Found this little blurb on the place for those interested.
The Space Power Facility
When it was constructed in 1969, the Space Power Facility (SPF) was the world's largest vacuum chamber. It stands more than 122 feet high, 100 feet in diameter and provides a vacuum environment for the study of space propulsion. Originally commissioned for nuclear-electric propulsion studies, the SPF has been re-commissioned for current and future use in the ongoing research and development of space propulsion systems. The SPF is located at Plum Brook Station, part of the John H. Glenn Research Center at Lewis Field, Cleveland, Ohio.