http://www.animate-onlineshop.jp/pn/pd/1167879/
Main cast kept from the drama CD (thank god - Yogi was basically made for Miyano Mamoru, and Kamiyan!Gareki is all sorts of awesome, I hope they also keep all the others, Yusakko /o/). A preview DVD will be bundled with the tenth volume of the manga, to be released on October 25: it'll contain footage of the anime and commentaries from the main cast.
There still isn't a single mention of the format of the anime in this month's ZERO-SUM, but the fact that they're releasing a preview like this seems to pretty much rule out OAD/OAV, in my opinion. I'm going to bank on a winter broadcast.