aclatraz

Can someone explain why Redis? Would one run a Redis server just for ACLs (separate from your existing db, say MySQL), or does this really only make sense if you're already using Redis? Edit: Looks to me like the store is programmable (http://github.com/nu7hatch/aclatraz/blob/master/lib/aclatraz...) -- I suppose one could build one for MySQL, or for Riak, or whatever. So, back to my original question... is Redis superior for this sort of thing?