Since Growl for Windows relies on some low-level Win32 APIs to do some of its window drawing, and I only have 32-bit systems to test on, I have been compiling it in x86 mode so that it will run in 32-bit mode, even on 64-bit systems. That works great for the main Growl for Windows app.
However, a side effect of this was that I made all of the supporting assemblies also compile for x86 - including Growl.CoreLibrary and Growl.Connector, which are also used by external apps to talk to Growl. That meant that any apps built using these libraries either 1) had to also be compiled in x86 mode, or 2) would crash when ran on a 64-bit machine. Not good, especially since more and more developers have 64-bit machines and the default Visual Studio compiler behavior is to compile for 'AnyCPU'.
More than a few developers reported frustration that the Growl .NET libraries were 32-bit only (and a few got bit by crashing programs that were compiled in the default AnyCPU configuration), so I decided to make sure the assemblies were 64-bit compatible. Since the code in those assemblies is 100% managed, it was an easy fix - I simply compiled those two assemblies in AnyCPU mode and all is well.
Now app developers can use the libraries in 64-bit apps and Growl for Windows itself still runs in x86 mode like it should (for now).