Apple has seeded the 4th developer preview of OS X Mavericks, and it’s available for download right now. The download, which comes in at about 1.27GB for users of OS X Mavericks DP 3, can be found via the Mac App Store app. For those of you not yet running OS X Mavericks, the download would normally be available through the Mac Dev Center, but it’s been down as a part of a well publicized security breach.

As you can see, I’m still in the midst of downloading the update, but I’ll be sure to report back with new screenshots and updates upon its completion.

Here is the new setup screen:

New iMessage sign-in: