Thanks to some quick feedback and troubleshooting from the OpenID WP plugin developer I’ve got things functioning again. It seems we turned up a few issues that will still need addressing (primarily regarding my use of Lighttpd vs the more standard Apache), but we have things functional again.
Big thanks to Will for his help. If you’re not using OpenID on your WP blog, check out the plugin.
Also, of course, if you continue to run into any issues with OpenID here please let me know.