The Future of Infinity Ward on IAMfourzerotwo is a blog entry from a few days back penned by Robert Bowling, Director of Communications and Community Manager at Infinity Ward (thanks Ant and Kotaku). The post mentions Infinity Ward's ambitions to create a new intellectual property in the future besides Call of Duty, one which they would control:

We’re excited to announce that in the recent months we have decided to reup on our contract with Activision publishing. The recently renegotiated deal may not seem like much of an impact from the outside perspective, but it has laid the ground work and kick started our future project, as well as the possibility of a unique new IP by Infinity Ward, that we’ll have complete control over. We’re excited to be working on our next project, but it’s going to be quite a while before I can share any details on exactly what that project is.