Using TFS2010, VS2010, Office2010 and IE9.
Link a work item to a document in Sharepoint following these instructions:
(As far as I know this is "best practice" if you expect to edit the document a lot)
Double clicking the newly created link in the work item will open up the document in ReadOnly mode. There is no option anywhere to edit the document or to enable editing. To do that I need to close the document and open it using some work around.
The quickest work around is to copy the url of the link and paste it into IE...