I've been asked about the v3 DG834G in the past (mine is a v2) and always answered that I don't know anything about it. Earlier this week Ben asked me about it and let me have a login to his. He also took pictures, which are on the OpenWRT DG834G page.
Some comments, based on this:
- The ADAM2 bootloader is different. Looking at the output of strings on it I can't see the checksum message seen in the v2 version. I also can't see the FTP server strings I'd expect. However the default config appears to specify an IP of 169.254.87.1 so it might be worth nmaping that when the router is coming up and seeing if anything is open.
- The wireless card is no longer on a mini PCI card. I assume it's still connected electrically the same way, but I guess this is cheaper for Netgear to manufacture.
- The CPU is slightly different, a TNETD7200ZDW instead of a TNETD7301GDU. No idea if this makes any major difference.
- The board appears to have JTAG and serial port headers easily accessible. And possibly even JTAG for the wifi.
I think it should be easy enough to get OpenWRT up and running on this (possibly someone has even done so already); someone just needs to hook up a serial console and do some prodding.