One of the more interesting features is Transients, which has just been added. Transients allow you do locally mutate some data in a very fast manner, without the possibility of leaking mutable data into the rest of your system.

Does anyone have any information on what's changed in 1.1?

There's a bit of a summary here:

http://www.infoq.com/news/2009/12/clojure-11-rc1-transients

Here you go:

http://github.com/richhickey/clojure/blob/1.1.x/changes.txt

Download the 1.1-rc1 zip file. There is a changes.txt file.

or read it here: http://github.com/richhickey/clojure/blob/68aa96d832703f98f8...