One of the most frustrating things about working with carbon nanotubes (and there are many!) is their variable electrical conductivity. Nanotubes can be metallic (highly conductive) or semiconducting. For the production of conducting polymers, you would ideally want all metallic nanotubes, but identifying and picking out just one flavour of nanotubes is virtually impossible.
There is, however, a new technique that allows these two states to be switched. Unfortunately its a bit of a fudge, using a high magnetic field to modify the tubes energy spectrum. It does however, point the way to future methods of altering the properties of nanotubes.