I have just checked in a major change to the Views API. Details can be found in the advanced help under api.html (and the handlers and plugins) pages, but the short version is that all handlers and plugins are now separated into their own files in order to conserve memory and not loaded unneeded code. This required implementing an API versioning system, and the upshot of this is that a new hook must be implemented by all Views modules: hook_views_api(). Without the proper use of this hook, the *.views.inc files will not be included.
