The samples are the best place to learn the use for the time being.
The Recast algorithm is explained in these slides:
http://digestingduck.blogspot.com/2010/02/slides-from-past.html
Few things have been added since, but the overall idea has remained the same.
In general I try to blog quite a bit about Recast and the development
process: http://digestingduck.blogspot.com
--mikko