Apple has released a new build of OS X Yosemite 10.10.3. The build is available both for developers, as well as for those enrolled in the AppleSeed beta program.
OS X 10.10.3 contains the much-anticipated Photos for Mac. Photos for Mac, which will replace both iPhoto and Apple's pro-centered photo app Aperture, lets users view, edit, and sort their photos, and has support for iCloud Photo Library built right in. Additionally, the update contains a number of stability and security improvements.
Source: Apple Developer Center