Data grid selected item command in mvvm

http://geekswithblogs.net/lbugnion/archive/2010/05/19/handling-datagrid.selecteditems-in-an-mvvm-friendly-manner.aspx

http://msmvps.com/blogs/deborahk/archive/2011/02/13/silverlight-mvvm-commanding-ii.aspx

http://asimsajjad.blogspot.com/2011/07/get-selecteditems-from-datagrid-using.html