A tidbit from Mark Millar I found on Ain't It Cool News regarding Vaughn's jump from X-Men:
"What we're doing is that 'Kick-Ass 2' is filming now, and next year we'll start production on 'Secret Service' which I did with Dave Gibbons, and Matthew and I have been talking about that for years. We thought Matthew was going to do X-Men first, but we found out there were actually a few imitators of 'Secret Service' in the works. People think you're lying when you say you're not trying to get your comics made into movies so quickly, but the two reasons it happens like that is first because it's the best ad for the comic you'll ever have. And for me, selling the book is the most important thing. The second reason is because people are always trying to rip you off. Somebody will start to work on a spec screenplay about your idea. There are three other projects I know of now about a James Bond kind of guy taking a street kid and turning him into a spy. Three screenplays were already going through Hollywood about this! So Matthew and I said, '**** this. We're not letting anyone steal our ideas.'"