I updated the roadmap with design and implementation ideas for imagery layers - https://github.com/AnalyticalGraphicsInc/cesium/wiki/Imagery-Layers-Details. I believe Scott will do some initial development work, and perhaps Dan will join at some point.
It is important that our layers API is friendly enough that an OpenLayers wrapper could be written above it. We don’t need to mirror the OpenLayers API - in fact, I believe they are making it more concise - but we shouldn’t also knowingly do things that would make a wrapper hard. OpenLayers is interested in WebGL and 3D. Given their widespread adoption, there is a mutually beneficial opportunity.