This is currently in the OpenWRT trunk, and while not an official marked release, if it builds, it usually builds something stable. :)

• the bootlog: http://wrt.scottn.us/openwrt-trunk-bootlog.txt

• Latest build is a contrib from @jdownj/twitter made 18feb2011 from fresh trunk. it includes openvpn. http://wrt.scottn.us/wrtu54g-tm-jdownj-openvpn.bin
• the binary: http://wrt.scottn.us/wrtu54g-tm-openwrt-devel-b5.bin (md5sum: 85e3a10b977f6f7c49359e87fd5d924b) (ChangeLog)
• b3 source: http://wrt.scottn.us/openwrt-adm8668-src-20101026.tar.gz
• now in openwrt trunk: https://dev.openwrt.org/wiki/GetSource

When preinit starts, SES light turns green. If you are holding the SES button, or at least press it quickly as soon as light turns green, then failsafe should start. Failsafe is indicated by orange light. Then you may telnet to 192.168.1.1 with a PC connected to a LAN port.

started a package repo of our own. we need _at least_ our own kernel modules right? try this in /etc/opkg.conf:

src/gz adm8668 http://wrt.scottn.us/packages
src/gz snapshots http://downloads.openwrt.org/snapshots/trunk/brcm47xx/packages
dest root /
dest ram /tmp
lists_dir ext /var/opkg-lists
option overlay_root /overlay
arch all 5
arch brcm47xx 10
arch adm8668 20

Since I never edited sysupgrade correctly in old version, I did this craziness to upgrade from the backfire build to these builds:

root@OpenWrt:~# source /lib/upgrade/common.sh 
root@OpenWrt:~# run_ramfs
mount: mounting mini_fo:/overlay on /mnt failed: Function not implemented
Please press Enter to activate this console. 
BusyBox v1.15.3 (2010-09-14 10:19:20 EDT) built-in shell (ash)
Enter 'help' for a list of built-in commands.
/ # cd /tmp        
/tmp # wget http://wrt.scottn.us/wrtu54g-tm-openwrt-devel.bin
Connecting to wrt.scottn.us (208.77.101.28:80)
wrtu54g-tm-openwrt-d 100% |*******************************|  2250k 00:00:00 ETA
/tmp # mtd erase linux
Unlocking linux ...
Erasing linux ...
/tmp # mtd erase rootfs
Unlocking rootfs ...
Erasing rootfs ...
/tmp # mtd erase rootfs_data
Unlocking rootfs_data ...
Erasing rootfs_data ...
/tmp # mtd write wrtu54g-tm-openwrt-devel.bin linux:rootfs:rootfs_data
Unlocking linux ...
Unlocking rootfs ...
Unlocking rootfs_data ...
Writing from wrtu54g-tm-openwrt-devel.bin to linux ...     
Writing from wrtu54g-tm-openwrt-devel.bin to rootfs ...     
Writing from wrtu54g-tm-openwrt-devel.bin to rootfs_data ...     
/tmp # reboot