The theme was a midcentury modern / atomic Christmas. Fun, right? I decided to suspend the centerpiece from the ceiling to allow for more room on the table. And chose a few shapes that were decidedly atomic / midcentury to build from moss and styrofoam. You can see the full step-by-step tutorial and a whole lot of photos here on DIY Network.
P.S. There are more awesome atomic Christmas ideas right here (stockings, ornaments, door wreaths, etc).