It looks like another month, another 10.8.4 seed, as a new download on Apple’s developer download site, build 12E47, contains the same focus areas as last month’s seed, Wi-Fi, Graphics Drivers, and Safari.
The seed is the fifth for this particular dot release of OS X. The previous release was April 23, 2013, while the seeds before that came out on the 1st, 4th, and 17th of that month.
Mac OS X 10.8.3 went through 13 revisions over a five month period, so this could just be particularly busy focus area changes.
The release notes bundled with the seed note that there are no other known issues at this time.
Source: Apple Developer