Amazon is reportedly working on an SDK for the Kindle.
"The Kindle Application Platform team is building the platform and SDK enabling developers to implement, deploy and manage applications for the Kindle."
What that means exactly for any home-brew community I'm not sure. It's not clear if it's going to be any open platform (hopefully) or not (most likely).
http://seattle.craigslist.org/see/sof/528585942.html