Now realistically this likely isn't a very big change for the company. They maintain Google optimized versions of many of the most popular Linux distributions already for internal staff and of course they've recently been pushing their cloud based app service particularly elevating the fact that it's platform independent (Microsoft, we stab at thee). However, the big chat on the web was that since the Windows Vista development fiasco, when Microsoft spent years and untold billions (everything seems to cost billions at Microsoft) fixing and improving security, the Windows OS is now much more competitive security-wise. Much was being made of many of the security features now built into Windows 7 that Mac OS X fails to sport.
The problem, however, for Microsoft has always been the fact that it's more problematic to live in a dangerous city with good locks and alarms then to live in a quiet town with your door wide open. Microsoft, with its extraordinary market penetration, is simply the bigger target while Mac OS X and Linux are often just not big enough for people to spend much time poking for holes in the armor. This is likely the reason for the Google switch.
Plus maybe it'll draw a bit more attention to the Linux-based 'Google Chrome OS' scheduled to ship this fall...
