Long cooked dashi

Has anyone else seen this? http://cookingissues.wordpress.com/2010/01/19/umami-nation-kombu-dashi-smackdown/ It's a blog I find really interesting (because I'm a geek), and I've been able to try out a few of their techniques using old equipment rescued from work. I haven't tried this dashi thing yet, but I've made "roast" beef sous vide* and it was stunningly good. *Vacuum packed, submerged in a 55°C waterbath for a few hours, then quickly seared on the outside before eating.