In Endless controversy about the correctness of significant papers, Denis Serre writes:
The research community is able to point out incorrect statements, at least among those which have some importance in the development of mathematics. In time, the errors are fixed; this is the role of monographs to present a universally accepted state of the art of a topic.
That kind of a role for monographs seems a healthy one, of course, but in the past it was not so uncommon that they also contained totally new results.
So I was wondering:
Are there recent examples (say, from the last 10 years) of books/monographs containing important new results?
I'm not talking about books in which the author, here and there along the exposition, strengthens some known theorem, adds a little detail, or improves/simplifies/unifies some proofs, etc... That is quite common indeed.
I'm talking about books primarily written to communicate new results, such as, for instance, Ruelle's Thermodynamic formalism (1978).
It seems from the answers and comments that the situation is more diverse than I thought, which is good, I think. Maybe it would make sense to "collect data" based on each field, because it's possible that in some areas publishing new results in books is more common than in other ones.