The Ubuntu development team have published a nice status page where you can readily monitor the development of upcoming versions of Ubuntu. From that status page, we learned that around 13% of the proposed work for Raring Ringtail is complete. One of the chief aims of Ubuntu 13.04 Raring, i.e. porting it to embedded and mobile devices is complete. However, only 1% of work is complete for Kubuntu 13.04.
The Ubuntu developers are quite busy in laying out the foundations of Ubuntu for Android builds. With just 112 days for the Raring Release, a lot of work needs to be done at a good pace in order to make Ubuntu 13.04 the best release ever.
Ubuntu 13.04 is mostly aimed at mobile devices such as laptops, netbooks, phones and tablets. While there are some experimental builds that show Ubuntu running well on Nexus 7, developers need to make sure that installation is easy and performance flawless on tablets and mobile phones. While Ubuntu runs well on laptops and netbooks, developers are focusing on decreasing the battery consumption which is currently not in par with other operating systems.
You can see the status page here.