
Apple today released an updated version of OS X 10.9.1 for developers, which has a build number of 13B40 . Today's release comes nearly two weeks after the second 10.9.1 beta, which had a build number of 13B35.

Registered developers can download the update through the software update tool in the Mac App Store.
Article Link: Apple Seeds OS X 10.9.1 Build 13B40 to Developers