Amazing Spider-man (Sony) Joins the Avengers (Marvel/Disney) Cinematic Universe .

Comic-Con: Andrew Garfield Wants Spider-Man To Join The Avengers – Gasp!

I like the fact that Andre Garfield is interested in joining the Marvel Cinematic universe. People are all over the place in how they would do it. Disney/Marvel, Sony and Fox combining all the movies together, finding continuity etc.
   In that aspect, Amazing Spider-man is easy. Norman Osborn  & Oscorp has always been involved in government/military contracts for technology development & weaponry. His work with the spiders was never meant to be used on human beings. Spider-man was an accidental side-effect, but the research that Peter's father was involved in could be directly linked to the Super-Soldier program mentioned in The Incredible Hulk and Captain America. As long as Sony keeps the door open that way, they could make references to Stark and S.H.I.E.L.D. indirectly. Also, in the comics(Ultimate Comics) SHIELD always said they were watching Spider-man but never got involved. This could be the one part to link Spider-man into the field.
  If Sony does want to join the party and leaves the Continuity openings, then there is no reason why Amazing Spider-man can't join The Avengers. Sony has a better chance of joining the ride then Fox does.  Fox has already written their own world using the X-men movies that basically leaves no room for joining Marvel/Disney's continuity. Sony Hasn't yet. They have a chance to move in, if they keep the storyline open. Having Spider-man join really is easy. All they have to do is shoot one scene involving Spider-man involved in the battle of New York against the Chitauri and then have a Spider-man meet-up with  Nick Fury, Hawkeye or Captain America and Boom, the rest is left up to simple creative writing.