Here’s a link to the latest entry by Michael Berger at Nanowerk’s nanoBLOG about the way scientists try to mimic intracellular molecular processes to try to develop biomolecular-based computer systems.
Flashbacks: Computer with DNA Circuits Plays Games; One Day to Go Diagnostic; Nanoactuator, a DNA Switch
The Road to Molecular Computing
May 31st, 2007 
Medgadget Editors Nanomedicine