Recently, Brian Michael Bendis (writer of Ultimate Spider-Man, Alias, Powers and Ultimate Marvel Team-up Featuring Spider-Man) announced the pending cancellation of Ultimate Marvel Team-up with issue 16. Bendis explained that there are a number of reasons for the cancellation including his work load, the amount of work it takes to produce the book and that the book was first conceived to have a finite run.
Part of the reason his workload is too heavy is because Bendis IS the writer for the MTV Spider-Man animated show. Apparently the new series will be based on the movies continuity.
All these details and more on the subject can be found in this months Powers #18.