Are all the movies based on Marvel comics set in the same universe or are they all set in different universes? There's not much evidence either way. In the comics they are all set in the same universe and crossovers are a common occurrence but in the movies there haven't been any crossovers (yet). There aren't likely to be any because the different movies are produced by different companies.
Can we assume that the movies are set in the same universe simply because it's like that in the comics, cartoons and games? The various different movies have very different styles; some involve pseudoscience, some involve magic. But it's like that in the comics too.
Another thing worth noting is that the X-Men movies are set in the near future (no more than 10 years judging by Magneto's age) but the other Marvel movies are set in the present.
What do you guys think?