Here’s a quick bookmarklet you can run on any Pinboard page containing a list of bookmarks. It adds a “Read” link at the end of the edit links for each post, and clicking the link will open the post in Instapaper Text view in a new page/tab. It also marks the post you click as “read.” Note that this happens whether you have that specified in the preferences or not (because it’s a quick hack and I think it’s weird to not mark an article as read when you read it).
This is a companion discussion topic for the original entry at https://brettterpstra.com/2011/01/04/pinboard-links-with-instapaper-text