One of the major keys to Windows 7's great success and massive rebound from the disappointment of Vista was the incredibly popular public beta test program that launched at the Consumer Electronics Show in January 2009.  Two years later Microsoft is well on the way to releasing the successor to the popular Windows 7, Windows 8, and it's reportedly preparing for a new beta program.

Softpedia reported last week that it received "Windows 8 Build 6.2.7959.0 Milestone 3 (M3)", an important preliminary build.  Compiled March 7, 2011 (based on the name string of the full build of the release), if authentic the build indicates that Microsoft Corp. (MSFT) is closing in on Build 8000 -- typically the build at which it launches a beta.

According to CentrumXP, developers now have access to "Build 6.2.7996.0.winmain_win8m3.110429-181" in the winmain_win8m3 branch.  The number in its build string (110429) indicates a release date of April 29, 2011.

That means that by now the Build 8000 may be compiled and almost ready to go.  It still remains to be seen, though, if the rumors are true and this is a beta build.  

One thing that calls that theory into question is the rumor that Microsoft will be working on Milestone 3 from February to July.  A finished build in May is way ahead of that schedule and doesn't quite add up.

According to rumors and leaks, Microsoft will wrap up Milestone 3, move on to a single beta, and finally air a release candidate before a commercial launch in late 2012/early 2013.  

Microsoft appears to be transitioning to a slightly faster release cycle, similar to what Apple does with OS X.  Whether that shorter release cycle will be accompanied by lower upgrade pricing remains to be seen.

The company is expected to possibly release the beta code to the broader developer community (only select developers have the current Milestone builds), and possibly announce a public beta at the Professional Developers Conference 2011 (PDC 2011) September 13–16, 2011, in Anaheim, California.

Microsoft CEO Steve Ballmer bills Windows 8 as his company's "riskiest product".  A preview that leaked about a month back showed a GUI similar to Windows 7, but with Microsoft Office's Ribbon inserted in new locations like the Windows Explorer.  Builds have also been seen running on ARM CPUs, which look to begin displacing Intel Corp. (INTC) and Advanced Micro Devices, Inc.'s (AMD) x86 designs in mobile computers and servers over the next several years.