Just called the GSB and was told that my check has been received. Turns out (and this I had neglected to see) the online application has also been updated and it now says Accepted Offer with the congratulatory letter replaced by another one verifying that my enrollment deposit is in and welcoming me again to the Class of 2007. That is some quick response on the online app, I must say.
Next steps: My undergraduate transcript is still sitting on my desk and needs to be mailed. Both my graduate transcripts are already in. And I need to send them a picture for the face book.