Pages, Numbers, and Keynote have been updated on the Mac App Store. Each app is $19.99, unless you’re upgrading to a new Mac or from a previous MAS version. Those who purchased box versions of iWork (back in the day) will need to pay the upgrade costs.
Apple announced the new iWork and iLife in a press release and during the keynote earlier today.
Update: For those with boxed/retail versions of iWork, Apple is slowly rolling out the ability to upgrade for free. Keep checking your “Updates” tab in the Mac App Store. If you already made a purchase today, you can hit “Report a Problem” in the Account section of the Store and request a refund.