http://huyrua.wordpress.com/2010/07/13/entity-framework-4-poco-repository-and-specification-pattern/ (good article)
http://stackoverflow.com/questions/4295975/repository-pattern-in-entity-framework-4-when-should-we-dispose
http://elegantcode.com/2009/12/15/entity-framework-ef4-generic-repository-and-unit-of-work-prototype/
http://elegantcode.com/2009/12/15/entity-framework-ef4-generic-repository-and-unit-of-work-prototype/ (good article)