These articles might be of interest...the series really gets into the advantages and disadvantages of a POCO approach.
http://blogs.msdn.com/b/adonet/archive/2009/05/21/poco-in-the-entity-framework-part-1-the-experience.aspx
http://blogs.msdn.com/b/adonet/archive/2009/05/28/poco-in-the-entity-framework-part-2-complex-types-deferred-loading-and-explicit-loading.aspx
http://blogs.msdn.com/b/adonet/archive/2009/06/10/poco-in-the-entity-framework-part-3-change-tracking-with-poco.aspx
In these articles the author mentions future articles that describe best practices in implementing Repository and Unit of Work patterns, but I can't find them. These articles are well written and I'd like to read more from this author.