Details are coming from the Optimus Project blog that say that we could be hearing about a sub $500 and sub $1,000 Optimus keyboard next week. The announcement next week should mark the day that you will be able to pre-order the keyboards.
The blog also states that the first batch of Optimus Maximus keyboards have been sold out and will begin shipping in December or January. The first batch of keyboards may be a little limited but firmware updates coming about once a month for a few months after the launch should bring them up to speed.