Yeah, load balancing is something that I think is integral to high availability and should really be made available - Elastix is a superb configuration tool for Asterisk, to really set it apart from other configuration systems would just seal that deal for me.
Vovida seems to have a good reputation with regards to load balancing - it seems that it works with Asterisk.
Obviously, having a solution that makes true enterprise provision would seriously put Asterisk on the map as a scalable, reliable and secure solution for the future.