I'm implementing OpenID with an MVC app and pretty much uses the MvcOpenID on CodePlex (http://mvcopenid.codeplex.com/), which also implements DotNetOpenAuth. My site work well locally, but somehow it doesn't work when deployed to my server. When tracing it with Firebug, it says "Failed to load http://www.kennysax.com/User/Login/ ...", but again, it worked locally, just localhost vs. my domain name.
If you want to check out, you can visit my site (http://www.kennysax.com - just a personal blog) and login with an supported OpenID provider...
Thanks.