Today, Microsoft announces about Outlook 2013 RT which will come with Windows 8.1 (earlier known as Windows Blue). This will come installed for free on all new Windows RT devices like Surface. As Windows 8.1 will be an free upgrade, you will get the Outlook RT with this update.
To know more about Outlook RT announcement, check out the complete post. I am also embedding a video which will give you first glance to Windows 8.1.