If you're part of the OS X 10.10 Yosemite beta program, you can now grab Developer Preview 4 from the Mac Dev Center. What's in the update is hidden behind the veil of the nondisclosure agreement, but members of the developer preview program can now download and install the latest version of the beta to both test it for bugs and (perhaps more importantly) develop new and updated apps that take advantage of the new stuff that Yosemite has to offer.
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