The news comes from Comic Shop News here.
I honestly think that Ultimate Spider-Man is the best ongoing comic *ever*. Sure there's stuff like Watchmen and Dark Knight Returns that's usually on the top of everybody's list, but they only lasted 4 or 12 issues. Even Preacher "only" lasted 66 issues. Sure not all of USM has been great, but for the most part it's been consistently good. To do so for 100+ issues, for lack of a better word, is simply Amazing.
I'm fairly sure Brian Michael Bendis was born to write Spidey. It's sad to see Bagley go. I never like it when art changes, and I'm actually more of a fan of art staying consistent rather than high quality. I hope whoever they pick up stays on for a while, cause I'd hate to get a "rotating" team of artists on the book.