THX-1138 - I don't see that happening for a number of reasons, firstly because Spiderman was only ever in with the east-coast Avengers, and you couldn't just drop him in it without having Daredevil and at least some of the X-Men, and maybe even the fantastic four (and they already stole one of them to be Captain America, can't have Chris Evans being Captain America AND the Human Torch in the same film.)
Secondly, Spiderman isn't part of the Marvel Cinematic Universe or MCU (search for 'Marvel Cinematic Universe' on wikipedia for more info) and hasn't been wired into that set-up from the beginning like the others have.
Thirdly, and most importantly, Spiderman is made by SONY, not Marvel films, and all the films in the MCU (and the ones planned around other Avengers-centric characters that are being discussed) are made by Marvel films.
It would be super-cool though, no pun intended. Imagine them moving on from that and doing the civil-war with Hugh Jackman's wolverine staring down Robert Downey Jnr's Tony Stark over Captain America's grave at the end.
So wish it would happen, but to do that they would have to wait for the licenses to revert back to Marvel, re-boot spiderman AGAIN, and re-boot the X-Men, and god I hate re-boots almost as much as I hate re-makes.
Jammill