We're just getting started with DataMapper too. Lots of things planned in the future as we refine the API and internals.

For example, we're looking towards allowing normal ruby objects to be persisted, not just objects that include DataMapper::Resource. I'm also working on a query/adapter layer that will allow more complex queries to be constructed similar to ARel called Veritas (http://github.com/dkubb/veritas/), except it will include alot of the things we've learned about working with 40+ datastores, some vastly different from RDBMS.