As of last night, here is the forum changeover status:
19-Sep-09 11:48pm GMT - \"All user profiles have been converted, along with quite a few other things, these were completed during Thursday and Friday morning. For the past 24 hours the converter has been working solely on converting posts, and it\'s now at around 65% completed (roughly 2.4 million posts processed).\"
We cannot give an expected time from this information, but the forums will be back as SOON as we can get them back. We will try to provide fresh updates as they come in.
