How to make sharing code between .NET and Silverlight (a little) less painful

Windsor ships for both .NET and Silverlight. However working with the codebase in such a way that we can target both runtimes at the same  time with the least amount of friction possible proved to be quite a challenge. ProblemWe’re using single .sln and .csproj files to target both runtimes (actually 5 of them, as we ship for 3 versions of .NET and 2 versions of Silverlight, but I digress) with