I've been writing some SharePoint web parts wich connect (as providers and consumers). I've found many difficulties, and (comparatively*) little material from the web, from books, or from microsoft.com, which is quite surprising as Web Parts have been around since 2003. This is making me think that although web part connections look like a first class feature in SharePoint, that in practice few people write connecting web parts, and few SharePoint users use them.

Is this the case - that few developers write connecting web parts, and few users use them?

*comparitively: A subjective impression. With each specific problem i usually find only a handful of web pages which address it, and as my problems seem to be fundamental ones (such which data type to wrap in an IWebPartRow), I expect a lot more search results.