Mac Rumors reports that Apple today seeded the first developer version of Mac OS X 10.6.6, known as Build 10J521, even before the company has publicly released Mac OS X 10.6.5.

Interestingly, the Mac OS X 10.6.6 update is only 3.7 MB in size, suggesting only very minor tweaks at this point.

  Apple Seeds First Developer Build of Mac OS X 10.6.6