updated 01:03 am EDT, Wed April 10, 2013
Release includes no new notes, but indicates new hardware on the way
[Updated with discovery of code for 802.11ac support] Apple is now seeding a second beta of OS X 10.8.4 to developers, reports say. The build is labelled 12E30, and as before comes with no known issues. Developers are also once again being asked to focus on Wi-Fi, Safari, and graphics drivers.
The new code marks a relatively quick turnaround for Apple, emerging a little over one week after the the first beta. 10.8.4 appears to be another maintenance release, with no new features. Apple may be saving any significant features for v10.9, which should be announced by or at this summer's Worldwide Developers Conference.
Researches poring over the code for the new release have uncovered support for the emerging 802.11ac standard, which implies that Apple plans or expects to release new hardware to support it, though when exactly cannot be determined. The new 802.11ac standard is a refinement of the 802.11n protocol and should result in faster network speeds and greater range on the 5GHz band.