Electronic topo quads will be available from the USGS map store in the next few weeks (apparently for free), according to All Points Blog. The goal is to produce new topo maps for the entire U.S., with each quad being updated every three years!
The updates are based upon the National Agricultural Imagery Program (NAIP), which I've covered before. The APB article goes into the merits (demerits?) of this, since it is summertime, "leaf-on" imagery. I'm not sold on the GeoPDF format yet either, but hey, at least USGS is making steps towards a faster update cycle.