tedster - 3:12 pm on Sep 1, 2010 (gmt 0)
Your analysis may be correct. It sounds like Google may have a problem with something in the past promotion for the domain. Parking alone wouldn't do it, but the second service you used does sounds suspect.
Not being inside Google, there's little I could say for sure. Almost no penalty is forever, but many of them simply stick around for a long, long time before they get released.
In the same situation, many have successfully moved their work to a new domain. But I understand that the domain itself is special, so you are reluctant to do that. Still, if it stays on this domain you may have a long wait. It may also magically appear in the near future. Strange things do go on. I know of one case where the company was specifically told the penalty would never be removed, and yet it was three months later.