If your like my company and have very large .net Apps, you can find your self in .net Dll Hell.
We currently have close to 30 projects for one Application... and growing daily
This article describes how to untangle the web:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnbda/html/tdlg_ch3.asp
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnbda/html/tdlg_rm.asp