That's just one set of jobs Microsoft is advertising, according to the Maddog web log, which tracks these things.
Other vacancies at Vole Central include staff to help create a new WinPE platform for OEMs, and a group that is meant to make clean installs for Windows in 10 minutes.
Perhaps the most interesting is the Nexus project group, which will design security and presumably DRM into the next version of Windows.
And other jobs to port .NET components to places where the Microsoft Sun never shines, such as the JIT compiler. µ