A Better 404 Page

Google's got a new little widget one can embed in a custom 404 error page that looks like this.  Its cool because in addition to a search box, it claims to be able to provide the user the closest matching page in cases of typos.  I am playing around with it for several of my sites, though I don't think it is an option for the blogs -- I am pretty sure there is no way to implement a custom 404 page on a typepad search.  By the way, the Google dashboard / webmaster tools site is pretty helpful, particularly if you are really interested in where and how your search traffic is coming in.  I implemented a new sitemap for each of my blogs and uploaded them to google via the webmaster tools site and saw an immediate increase in search hits.