A preview image for RPiBuntu 16.04 is now available here.
This preview contains two 4.1.19 kernels. One with the default configuration and one with an enabled VC4 module for the GPU in the Raspberry Pis. The VC4 kernel is available in the wily/armhf-testing/ repository but only the new 16.04 release contains the necessary mesa and Xorg versions that support the new driver and its features. This preview image is configured for the VC4 kernel which will also be loaded by default. Please note, this is a preview release with unreleased and unstable software! Use at your own risk.
The MD5SUMS and the script to create own images can be found on GitHub. If you find bugs or have any problems, please open an issue on GitHub.