A while ago I worked (briefly) on a product called BuilderBooster. This program is an addon for Borland's C++ Builder which has the ability to share the building of projects across a group of networked machines by sending source files securely over a local network connection to another borland compiler. On most projects this was able to speed up build times significantly (we got one project down from around 30 mins to 15 secs).
The big question is, does anybody know of an existing solution for doing the same sort of thing with a Microsoft compiler for C# code