iSCSI boot driver 0.2.5 (isboot.ko) has been released.

[Daisuke Aoyama]

You can download the source file from:
http://www.peach.ne.jp/archives/isboot/isboot-0.2.5.tar.gz

Also, you can download a demo version of 9.1-BETA1.
http://www.peach.ne.jp/archives/isboot/demo/FreeBSD-9.1-BETA1-amd64-memstick-isboot-0.2.5.img

This demo version is added isboot.txz which includes isboot.ko and 
loader.conf
and a syscons patched kernel for DN2800MT.

You can use it as istgt's LUN extent like this:
----------------------------------------------------------------------
[LogicalUnit2800]
  TargetName "iqn.2007-09.jp.ne.peach:aria:dn2800mt-boot"
  Mapping PortalGroup4 InitiatorGroup2800
  UnitType Disk
  QueueDepth 32
  LUN0 Storage /tank/iscsi/istgt-DN2800MT.vdi Auto
  LUN1 Storage /tank/iscsi/FreeBSD-9.1-BETA1-amd64-memstick-isboot-0.2.5.img 
Auto
----------------------------------------------------------------------

Then, boot FreeBSD installer from LUN1 and install FreeBSD by normal way to 
LUN0.
After installation, you have an iSCSI based diskless machine.
I have tested it with iPXE(USB boot) and Intel Desktop Board DN2800MT 
without using SATA ports.

For example, booting LUN1 by iPXE(just use :::1:):
sanboot iscsi:172.18.0.26:::1:iqn.2007-09.jp.ne.peach:aria:dn2800mt-boot

For more info of Japanese is here:
http://shell.peach.ne.jp/aoyama/archives/2097
http://shell.peach.ne.jp/aoyama/archives/2100

Have fun!
Daisuke Aoyama