Microsoft has been conspicuously absent in the tablet explosion that has taken place over the first half of this year, but according to Bloomberg, that's all set to change next week. The news site references three anonymous sources who say the software giant is planning to unveil a new tablet OS based on the next generation of Windows. Unlike Windows 7, the new operating system will be compatible with ARM processors-- the same chips used in the iPad and many Android-based tablets. No word yet on who Microsoft is aiming to team up with on the hardware front. The announcement is expected to take place at technology site All Things D's annual D conference.