I wrote a bookmarklet to scratch an itch. It parses the current page in your browser for a RevCanonical link and sends that to Twitter as the base of a tweet. I mostly plan to use it to tweet about Flickr photos but you can use it on any page that has a RevCanonical link.
Bookmarklet Source Code:
javascript%3Afunction%2520traverse%28w%29%257Btry%257Bvar%2520l%3Dw.document.getElementsByTagName%28%27link%27%29%3Bfor%28var%2520z%3D0%3Bz%3Cl.length%3Bz++%29%257Bvar%2520c%3Dl%255Bz%255D%3Bif%28c.getAttribute%28%27rev%27%29%3D%3D%27canonical%27%29%257Breturn%2520%27http%3A//twitter.com/home%3Fstatus%3D%2520%27+c.getAttribute%28%27href%27%29%3B%257D%257Dfor%28var%2520i%3D0%3Bi%3Cw.frames.length%3Bi++%29%257Bvar%2520url%3Dtraverse%28w.frames%255Bi%255D%29%3Bif%28url%29%257Breturn%2520url%3Ba%257D%257D%257Dcatch%28e%29%257B/*%2520use%2520e%2520or%2520do%2520nothing%2520*/%257D%257Dvar%2520url%3Dtraverse%28window%29%3Bif%28url%29%257Bwindow.location%3Durl%3B%257Delse%257Balert%28%27There%2520is%2520no%2520canonical%2520shortlink%2520for%2520this%2520page.%2520%255CnMaybe%2520you%2520should%2520try%2520a%2520Flickr%2520photo%2520page%3F%27%29%3B%257D
