With the controller revealed a week or two ago, the speculation of the consoles shape is under heavy speculation. We see lots of mockup, some practical and many fantastical. Some interesting takes on classic PS shapes from teh past, and some very dull utilitarian shapes we have seen before.
I think Sony will make something very PS2 like - a slab -that has its own very simple and clean design. I think without a doubt it will be two tone. White and a dark grey like teh controller. That will be the stocks primary color for launch. I also think that their intention is color or adornment will come from buying the wrap of your choice from any of the companies offering device wraps. I think Sony will very intentionally be offering a blank canvas, a form easy to wrap and a form that shows off the graphics of you choice well.