As I've been careful to mention on the Windows Mobile Developer Wiki, in order to develop applications for Windows Mobile 5.0-based devices (or more accurately, make use of the new Windows Mobile 5.0 features), you need to buy Visual Studio 2005. The good old eMbedded Visual C++ Toolkit won't allow you to create managed code, or make use of the Windows Mobile 5.0 APIs. (Also, the lowercase "e" and uppercase "m" was really starting to drive us mad here in the User Assistance division.)
Now, rather embarrassingly, Microsoft managed to mess up the packaging on the Visual Studio 2005 boxes, and so this might not be entirely clear. However, you can use Visual Studio 2005 Standard Edition to develop for Windows Mobile devices. The Standard Edition costs about $260 from retailers like Amazon, which I know is $260 more than the eMbedded Visual C++ Toolkit, but is still one heck of a bargain when you see the improvements and new features.
I think we should get whoever made the typo to give us some copies to give away for free. What do you think?