Apple today seeded the first beta of OS X 10.10.3 Yosemite to developers, just over a week after releasing OS X 10.10.2 to the public. OS X 10.10.3 includes the much-anticipated Photos app for Mac.The new is available through the Software Update mechanism in the Mac App Store and should be available in the Mac Dev Center soon.
Recent rumors questioned the removal of mentions of the Photos app for Mac from Apple's website, suggesting it might be delayed, but today's beta release indicates that it is still on track for an early 2015 launch.
Apple Seeds First OS X 10.10.3 Yosemite Beta to Developers With Mac Photos App