vBSEO is a very nice vBulletin mod. I have it on one of my forums, and it did a world of good for SEO, and organic search engine results (not to mention it makes the links look very nice). It would help DP grow even more!
I would actually be amazed if a webmaster site this large used something like that... Though if they did install it here, it would likely do WONDERS for [vBseo] sales! I personally don't like the fancy urls, so I'm against the rewrite portion of it.
this has been discussed to death...shawn will never put it because that's just how he is, and the usual argument that DP already ranks for every keyword under the sun.