Having similar issues on my end....
My registered site is pointing to the correct port #, but the wrong IP address. My ISP replaced my cable modem a week or so ago, and my IP address changed as a result. I never noticed it until today, as I normally don't use the "sitename.subsonic.org" address, since I have my own "sitename.domain.com" address that does the same thing as the subsonic.org address.
I noticed the problem when I tried using iSub on my iPhone... the address was still pointing to my old IP address, and I couldn't change the configured server setting to my own domain.com address in iSub, so I tested the subsonic.com address on my PC, and that's when I actually noticed the IP it was forwarding to was still my old one.
Checked settings in Subsonic, and the subsonic.org domain forwarding was actually disabled. Re-enabled it with my site name, and was forced to re-enter my license key (no problem there), but it still won't connect. I'm assuming it will just take a while to register my new IP address in the DNS records, so I'll wait a couple hours, but after that, I think I will either have to change my site name, or maybe contact Sindre directly to ask if the update can be done manually...

Edit: Update - seems to be working now, although for some reason, the subsonic.org address forwards to the local IP address of my Subsonic server (192.168.x.x) on port 4040, and not my public IP address. But my iphone using iSub must forward to the public IP address, because I can still access server playlists and non-cached music when I have wifi disabled, and am going over 3G. (I think this may have been the reason I created my own domain in the first place!)