Stanley Williams & colleagues at HP have published a very interesting article relating to their work on molecular scale logic. This paper builds on previous research at HP into molecular scale memory structures, however whats new is ability to latch using a cross-bar architecture, and this represents the final requirement for computing with molecules. Dont sell your Pentium just yet though-with switching speeds of only 100Hz (compared with GHz for current CPUs), and a lifetime of only hundreds of cycles, there is much work to do before silicon has a worthy contender. (Its worth noting that the human brain works at a clock speed of some 10Hz, as far as you can apply measures such as clock speed to something so sophisticated, so faster is only better with current architectures, a fact that hasnt escaped the team at HP)
Nevertheless, its probably the most successful step to date towards the creation of a workable system of molecule electronics. Watch this space