Looks like Nu Horizons (http://www.nuhorizons.com/) has 2800 ATmega328P-AU chips in stock. They had 3000 earlier today, until I and someone else each bought 100. Also it looks like Digikey had 3000 earlier today and they are either already gone or will be available later.
Here's hoping these aren't counterfeit, like Sparkfun discovered a while back. At least Nu Horizons hasn't caused me any problems with orders in the past.
I have ordered from them in the past and had no problems, but not in the past couple years. Not really concerned that they would knowingly sell counterfeit parts, but I have no information about how well they check out their suppliers.
Nu Horizons ran out of the remaining 2800pcs the other day, but Mouser now has these in stock. Over 800pcs. Seems like they are trickling out to distributors a bit more now.