Once we get a solidly compiling tree, I'm going to start with this:
Make each layer's wireframe a different color in the 3d windows, that color being selectable by the user. Perhaps you could also select on a layer-wise basis to use the layer-defined color for that layer's wireframe display or the main color (is it exists) from that object's material.
After I get that working, I'm going to try to make the ability to display a layer without having it's objects selectable (aka locking a layer). What these two minor things would do for the workflow of complex projects would be amazing.
I'm planning to do this myself, but I'll ask anyway... any comments?
viewable but unselectable object could be achieve now by the scene and the use of 'set' for the rendering.
Yeah, I know you can do it now via the scene/set workaround. But this would be sooooo much better. And it's (probably) within my grasp as a programmer.
another useful tips would be to select layer by object. select an object and click to isolate his layers.
implement rendering in layers
Wireframe colors have been a debate internally as well.
Biggest problem to change is that it uses a context-driven system now. The color tells about the selected/unselected state, and the type of data (from a library, from another scene , a key from an Ipo, etc)