Re: Iron Man 3 Discussion/Photos/ETC.
Essentially, if it's mentioned or seen in a FOX-produced Marvel film, FOX holds the rights to it from there on out (which is one of the reasons there were so many fucking worthless and pointless cameos in The Last Stand and X-Men Origins).
Those characters are part of the package of rights whether they appear in cameos or not. The producers include the cameos because they think fans get a kick out of them.
"I'll see you in another life, brother."