Here’s a gotcha that got me.
It is not immediately obvious, but visual studio stores in it’s sln file a set of project configuration selections for every combination of solution configuration and solution platform.
The gotcha is that by default Visual Studio (all versions 2008-2012 as far as I know) only show one half of that combination in the standard toolbar, so you can get in a situation where one of your developers is building something completely different to everyone else as somehow the platform has silently been changed.
I recommend you add Platform to your toolbar so that you can always see what you are about to build.
And if possible, remove any unused platform configurations from your solution entirely.