I just attended the "SharePoint 2007: Creating SharePoint Applications with Visual Studio 2008" session by Chris Johnson, who's a Program Manager on the SharePoint team. The session itself was ok, but not really shocking if you've worked with the Visual Studio Extensions for Visual Studio 2005. The more revealing bit was the Q&A at the end of the session.
When asked questions about updating list en content types features Chris answered that the best practice for updating the lists and the content types is actually to build a new feature with a featurereceiver, where the featurereceiver will contain code to update the list or the content type. This means that the feature itself will have no functionality, we just need it to get the featurereceiver to run the code to perform the updates.
A lot of people already decided that this would probably be the best and most solid way to update lists, libraries and content types, but this was actually the first time that I heard someone from the SharePoint team actually saying that this is indeed the best way to update.