@jimp:
Actually NAT+IPsec is still not possible even on 2.0. If you have overlapping subnets and you are forced to use IPsec, you'll need to setup a second box to translate through, like so:
Main Firewall, IPsec tunnel between "fixed" subnet and remote site, LAN interface as usual, second internal interface on the "fixed" subnet.
Second "VPN" firewall sitting on the "fixed" subnet on its "WAN" connected to the main firewall. LAN subnet is the same as the LAN side of the main firewall, but a different IP. This box's job is just to translate between subnets.
Main firewall gets a static route that points traffic headed for the remote subnet to the VPN router instead, which should make the NAT happen, and then when the NAT goes out via the main firewall it's on the right subnet, will match the IPsec SPD, and go over the tunnel as you like.
That method should work on 1.2.3 or 2.0.
Maybe this post will give some tips about implements it in one box
http://fixunix.com/bsd/87865-nat-ipsec-openbsd-pf-isakmpd.html