Hey Tony,
I'd give it a day. If you still haven't gotten a response, send an email to Sedo. The buyer will need to fund his account before anything goes further. Recent posts here (and elsewhere) have suggested a 1:1 payment to nonpayment with Sedo. Granted your domain was bid on buy Zong.com (presumably), this isn't an issue however I'd imagine Sedo chose not to email you until the buyer has funded his account for this reason -- there really is no reason to alert you until the name has actually been payed for. Much like eBay, you don't have to fund your account before placing a bid. Once the buyer funds his account and makes the purchase, Sedo should send you an email asking you to prepare the name for transfer. I don't do business with Sedo myself, however, I've heard they're quite slow -- especially lately. If things don't work out with Sedo, you can always do the transaction through Escrow.com -- my preferred route personally and it's much quicker.