As far as I know, it is like SLI and only runs one display when you actually are using Crossfire, which is to say that both GPUs are combining their power to drive one display quickly in a game, as opposed to simply having both cards installed and the little Crossfire jumper connected. Read ATI's answer carefully:yes. look at the link below at the crossfire faq.
http://ati.amd.com/technology/crossfire/faq.html
8. Can I use the CrossFire platform to drive multiple displays?
A. Yes, the CrossFire platform will work with ATI’s SurroundView™ multi-monitor technology to enable up to 5 separate displays when not running in CrossFire mode.