I would note of interest an article (just look at the pictures) from the recent Intel Developers Forum (IDF) to see where Intel intends to go. They are planning for chips based on a 22nm process by 2011. On a more subtle note they appear to be seriously considering 'die-stacking' to allow the 'chips' to grow in 3D. This has the potential of significantly reducing interconnect delays between processors and memory and/or stacked multi-processors [see Note 1]. That would imply significant performance improvements without having to figure out the messy process of trying to wire chips with buckytubes or DNA.
The only thing one can say is that the next decade is definitely going to be the "nanodecade" [see Note 2]. Note 1. I can see stacking the processors on top of the memory or perhaps interleaving the processors between the memory but stacking multi-core processors (think 4×4 or 8×8) suggests that one is going to have to go out and find a fire-hydrant for the water supply to keep the PDA or cell-phone cool if you expect to be doing conversions of entire movies from low-definition to high-definition in real time (which requires all of the processors be active rather than just sitting there…). I can see the coming complaints along the lines of "Your last email just melted my cell phone! You owe me $5 to purchase a new one."
Note 2. I would almost have expected "nanodecade" to be a new word but Google finds several references. (The first of which involves one strange fictional usage I wouldn't have quite anticipated…)