Thanks goodness for comics business and commentary site ICv2.com for its handy round-up of the recent mini-avalanche of exclusivity deals between various creators and Marvel Comics. Although I'm less familiar with Marvel's version than some of the DC Comics versions -- and then only in an anecdotal fashion -- exclusivity deals lock talent into work for a specific company, sometimes with exceptions for particular outside work, in exchange for things like a cash bonus (on signing and/or on completion of a certain amount of work) and access to a healthcare plan. Again, I don't know what's at work here or on anyone's specific contract.
Anyhow, these are worth noting for what it says about publishing strategies, particularly on mid-level books where there is not likely to be a strategy of short runs by today's hot freelancers. A few exclusivity deals help ensure a pool of talent with which to work that is not going to jump when a position opens up elsewhere on perhaps a more attractive project in the short-term, or even may guarantee a phantom reserve unit when those kinds of slots open up at your own company.
Some "meet the new kids" Marvel art by exclusive contract signee Michael Ryan