In a previous post (http://blogs.msdn.com/allend/archive/2003/10/16/56791.aspx) I ranted about a weird behavior in generating Interop Assemblies where case changes occured in function names.  Well, it turns out that the TLB is the culprit.  All methods therein are case insensitive (the VB standard).  The first method into the TLB wins when it comes to the case for all similarly named functions.  So if you have Foobar and FooBar functions in your IDL, they'll both end up with the case of the first one in the TLB and in the Interop Assembly for the TLB.  (I found the info in Adam Nathan's .NET/COM Interop book, THE definitive source for practically all Interop information.)