According to wendyj, the Microsoft Certified Application Specialist (MCAS) will be rebranded to Microsoft Office Specialist (MOS) at June/2010.
It seems that the new brand (MCAS) like MCITP doesn't heard by many employers.
Many of the employer's still only knows about MCSE but not MCITP (We can find it out from the recruit).
Besides, there are far too more MOSs than MCASs in the world.
Anyway, there will have new logos for the MOS.
About the old MCAS certificates or cards with MCAS logo, you may use them for lighting up the BBQ stove. :)
