Haven't looked to see if anyone has reported it yet, but I just played Goose Green on the CIA server, and I discovered that if you aim the brit m79 grenade launcher while riding in the back of a transport truck, you get the AAV hud.
Kind of a funny bug, but I didnt get a pic.
To produce it, I just hopped in a transport truck (rear passenger seats), pulled out my m79, and aimed it. Result was the AAV sights showing up.