Apple today seeded the first beta of OS X 10.10.4 to developers, just over a week after releasing OS X 10.10.3 with the Photos for OS X app to the public.
The new beta, build 14E7f, can be downloaded from the Mac Developer Center.
OS X 10.10.3, released last week, was the first major update to OS X Yosemite that brought new features, including the Photos for OS X app, a redesigned emoji picker, and new diversified emoji.
Article Link: Apple Seeds First OS X 10.10.4 Yosemite Beta to Developers