Microsoft has reportedly passed the 7200 build string milestone in the development of Windows 7. At the same time, reports indicate that the Redmond-based company is also building and testing the first Service Pack for the next iteration of the Windows client and server operating systems, even though both Windows 7 client and Windows Server 2008 R2 are yet to hit the RTM mark, let alone general availability. Wzor has leaked screenshots of Windows 7 Build 7138 and Windows Server 2008 R2 Build 7138 with Service Pack 1 already installed, and now the peek behind the Win7 scene coming from the Russian website is Windows 7 Build 7200.

According to Wzor, Windows 7 builds in the main branch, winmain, have jumped from 6.1.7141.0.winmain.090528, compiled on May 28, all the way to 6.1.7225.0.winmain.090529, wrapped up on May 29, in just a single day. Microsoft apparently passed a very important milestone in the development process of Windows 7 on May 29, but there are no details available as to what exactly happened. Still, the Redmond-based company is set to unveil all changes by the end of June 2009.

Nonetheless, it appears that the Windows 7 development process now has two directions, and two main branches. Such a move implies that Windows 7 has gone through a forking, a strategy designed to split the build tree in order to accommodate builds from two branches. Microsoft did that in the past with Windows 7 RC and RTM, and it is now doing it again with RTM and SP1.

In this context, the main branches of Windows 7, after the fork, are winmain and winmain_sp. In order to support half of the forked tree, Microsoft is also producing builds in the winmain_win7ids branch. The latest builds of Windows 7, from all branches, are 6.1.7200.0.winmain_win7ids_sp.090529; 6.1.7225.0.winmain_sp.090529 and 6.1.7225.0.winmain.090529. No official comment from Microsoft as of yet.