Thought I would add a few data points for anyone else interested in this.

9/12/2013 - Filled out online Skymiles Medallion Status Match Challenge form
9/12/2013 - Unprompted, I emailed a picture of my United Premier Gold Card to [email protected].

Never received a reply of any kind. Then,
9/26/2013 (exactly 2 weeks from original submission) - logged into Skymiles account and Current Year Status now shows Gold Medallion with effective dates of 9/26/2013-12/26/2013. Looks like I am set for the challenge. Now to make sure I hit my 16K...

EDIT:
9/27/2013 - received email from Delta confirming status match challenge