Yee, Fisher, Dhamija, and Hearst, a combination of Berkeley CS and SIMS folks, devised some effective animation techniques for radial tree layout, a few years ago. Radial tree layout is a focus+context visualization technique for showing graphs. The only place I've seen their methods show up is in the prefuse toolkit, but I'm not really deep into infoviz. Mainly parking so I can dig into the roots of radial tree layout.