Apple seeded the third beta of OS X Yosemite 10.10.2 (build 14C81f) to developers on Friday. The new seed comes just over two weeks after the release of the second beta.

The new beta seed is available via the “Update” tab of the Mac App Store, and via download from the Mac Dev Center.
OS X 10.10.2 is a minor update, and will include bug fixes and performance improvements to the operating system.
Apple’s release notes ask developers to concentrate on testing Wi-Fi, Mail and VoiceOver. The update is likely intended to fix some of the still lingering Wi-Fi issues users have reported since the release of OS Yosemite 10.10.0.
(Via MacRumors)