Yeah, I saw this on HN and it completely made my day. I've been using Datomic for a few months now and I'm really happy so far. It's just f#$%ing brilliant in my mind.
Looks like Rich Hickey is on a tear - which is great news for all of us! BTW, http://blackstag.com/ is very nifty too - thank you for all the stuff on Clojure.
For those new to Datomic, probably the best way to get your mind around Datomic conceptually would be to watch these introductory videos[1] Rich and Stu put together when first introducing Datomic. It's pretty revolutionary, IMO.