Apple has just seeded the first beta of OS X 10.10.5 to developers. This comes two weeks after releasing 10.10.4 to the public. 10.10.5 is likely going to be the last update to Yosemite before the release of El Capitan this fall.
According to the release notes, this version improves the stability, compatibility, and security of your Mac. That’s all we know right now, but when more info is discovered we’ll be sure to update this post.
Developers can download the latest beta of Yosemite in the OS X Developers Center.