Cycles aims to be a render engine for individuals / small studios, aimed primarily at rendering animations. This goal is what we evaluate priorities of features by.
For 2.68, the following features are planned to be worked on:
- Hair shader
- Ubershader (combined diffuse+glossy+transparent node)
- Look into of improvements for SSS, AO, mist, ..
After this the next big feature will be Volumetrics. Probably the first release with Volumetrics will be 2.69 or 2.70.
Beyond that, there is a feature list which contains other small and bigger features we'd like to add eventually.
If you'd like to help out, you can look in these places:
If you need more details about how features should work, how to implement things or just to announce that you're working on something, contact the bf-cycles mailing list.
There are some things obviously missing that people would like to see added. Bidirectional path tracing, photon mapping, MLT and similar algorithm are not a priority for me, since we do not believe they are the main possible performance improvements for animation frames.