Not sure of it's possible, as it normally need one end to have static IP.
There's a feature called DMVPN for dynamic VPN connectivity, but only for routers.
Yes, this is possible.
use one of the Remote access VPN setups and use a DynDNS client to update your VPN Servers IP address to a DNS entry.
How to Configure the Cisco VPN Client to PIX with AES:
BTW, do you mean dynamic VPN for site-to-site, or remote access?
For remote access (by vpn client), this is possible & common. For site-to-site, this is rare.
I'm going to implement site-to-site vpn with pix, Both site A & B using dynamic ip, i can do that with linksys router using no-ip, but not sure with pix-to-pix because so far what i know pix using ip address to set the peer and receive the peer, eg.
isakmp key ******** address 0.0.0.0 netmask 0.0.0.0
crypto map mymap 10 set peer 200.x.x.x
isakmp ket ******** address 200.x.x.x
Not sure if can replace address with domain name instead :) he..he..he