1.	My company, UserLand, has a product in development called My.UserLand On The Desktop that supports both sides of this format. You can use it to create channels that have <item>s with <enclosure>s, and it manages downloads for these channels. So it's both an authoring and viewing tool.
2.	It's a bootstrap, and it's open, meaning that anyone can develop software that works on either or both sides of this connection.
3.	Adam's company is doing a graphic environment for music and video on PCs in Java. Others are welcome to join up and do software for all kinds of computers, content and people.