Marvel movie crossovers and cameos?

recently in movies fro marvel there have been a few cross overs or cameo appearances or nods to other movies iron man and hulk being the main two culprits this is where my question lies



CAPTAIN AMERICA



ok i didnt see it in the hulk til i googled it but i saw it in iron man double and triple checked and then googled it to be sure n there as dammit is captain americas shield behind iron man as hes trying the armour on n the machines have him lifted n pepper walks in il post links after.



anyway question being i know these 3 characters are the avengers but is there anything official as to why captain america is popping up everywhere



http://www.filmschoolrejects.com/news/found-captain-america-in-the-incredible-hulk.php



http://www.youtube.com/watch?v=Y9pNgJeAZTc



have to watch for the iron man one but it tells u whenMarvel movie crossovers and cameos?
yes there is going to be lots of marvel movies that lead to The Avengers in 2012.



just before the avangers is released, The First Avenger: Captain America will hit theaters on July 22, 2011.



thats basically it, just hinting that there is going to be a Captain America movie and what leads up to The Avengers movie.