[Asterisk-Users] virtual pbx

[Andres E. Moya]

Is it possible to set asterisk up as a virtual pbx like in apache and 
virtual host?  If so can someone point me to the right direction.
I would also like to setup asterisk with some type of redundancy, I have 
searched the lists and googled but havent really found anything, I would 
be willing to put together a paper if I had the info and make it 
available, through asterisk doc project or voip-info.org or which ever.
Any help would be greatly appreciated.
Thanks in advance,

Andres Moya