The Nexus 9 Keyboard Folio is available only in black and is listed as leaving the warehouse in 1-2 business days. With it being a holiday week in the United States, that would have the case on your doorstep by early next week. The case folds into two angles optimized for typing and consuming media. It attaches magnetically to the tablet and uses Bluetooth to pair the keyboard. Google claims the keyboard can last up to 5 months on a single charge.
Not long after it went up for pre-order on Amazon, the Nexus 9 Keyboard Folio went out of stock and many users who pre-ordered it are still waiting on the case to arrive. For now, the best and quickest option for a Nexus 9 keyboard case is the official offering from Google and you can get it on the Play Store now.