Found your site while Googling the above as I think someone had similar queries about a signed Iron Man 3 cast poster.
Saw this on eBay yesterday:
http://www.ebay.co.uk/itm/190865109606?ssPageName=STRK:MEWAX:IT&... and basically wanting to know if this is legit or not. I think someone said that the logo's etc could be fake.
There's a couple of others on at the moment like The Lone Ranger with similar listings: (http://www.ebay.co.uk/itm/The-Lone-Ranger-DS-Movie-Poster-CAST-SIGN...)
I'm also curious about this item (and I guess the seller) as he has some pretty impressive items on eBay. I am by no means an expert on signatures but the majority of these look very real.
Any help would be gratefully appreciated!