So what we do now is, on submit, store a "pending comment" (which gets a number), send the user for their OpenID auth loop, and when they come back, finish posting their comment. One of our regular maintenance tasks keeps the pending comments table clean, giving users a more than reasonable amount of time to finish the auth loop.
All very straight-forward, but I'm excited about it because this afternoon the DeadJournal guy (scsi) updated his beta-site with the new code, and I was able to leave comments back and forth from LJ's beta site and DeadJournal's beta site. This has been on our wishlist for 3-4 years now.
Probably as of tomorrow we'll update the production LiveJournal.com server code and DSA support will be gone. LifeWiki.net will also be updated to use the new consumer library. The new libraries are not backwards compatible with those being run on these two sites.
Currently the following sites have both OpenID server and consumer support enabled:
Your identity URL would be something like http://trinary.deadjournal.org/users/daveman/
You cannot currently comment between the two GoatHacks. Haven't fully investigated this issue, but is on my list for the morning.
We'd love you guys to test this out and play around with it. We've had one of Six Apart's awesome UI guys take a look at it and done a good range of browser testing, but the more the merrier. Constructive feedback, bug fixed, suggestions, etc are always appreciated! Code is in CVS if you'd like to review it and is easy to enable on your own install, $LJ::OPENID_SERVER and $LJ::OPENID_CONSUMER in ljconfig.pl respectively. Debian packages, that I built this afternoon, for the required modules can be found at http://goathack.livejournal.org:8064/debs/.
Anything I left out, ask.
More information on OpenID can also be found on the mailing list (http://lists.danga.com/pipermail/yadis/2005-June/thread.html) where I also stole part of this post from. ;)