Overview
It is now possible to run a ros master on windows - either via the Msvc Sdk directly or via the Msvc Build Environment.
Instructions can be found in each of the tutorial links above.
Status
Currently what works:
- roscore
 - rosversion
 - rostopic, rosservice
 - rosparam
 - roslaunch
 - rosbag
 
What hasn't been implemented yet:
- rosrun
 
Others may work (more or less) but I haven't tested them yet.