The ElderSpirit cooperative in Virginia, which has been occupied since 2006, is one of only a handful of dedicated elderhousing cooperatives that have gone beyond the planning phase to the point of fruition. Here's a story about it.
If you share Elderspirit's values, and are looking to buy into a community, it seems very well-priced: This two bedroom townhouse, walkable to town, library, farmers market and more, was recently listed for less than $110,000.
You can read more about ElderSpirit at its website.