Sorry. You're going to see a lot of articles on the internet today happily proclaiming "An X-Men/Spider-Man movie crossover!" but unfortunately, you should not be excited about this seemingly momentous news, and here's why.
It's because an X-Men: Days of Future Past clip or trailer will play after ASM2's credits. There's no connection between the two, other than Sony allowed Fox to insert their movie clip presumably after paying them a great deal of money. In no way does this indicate an actual movie crossover other than the fact that if Fox and Sony managed to work together for what is essentially a glorified commercial for one of the superhero franchises, then maybe 10 years from now they'll allow Peter Parker to pass by Wolverine on a New York City street or something, but I wouldn't hold your breath.
And actually, at the moment the only place where ASM2 is confirmed to include the DOFP clip is in the UK; it might not even happen here. Sorry, folks. That Spider-Man and His Amazing Friends movie is still a long ways off.