One of the possible downsides of hydrogen fuel cells being used in cars is the expense of the platinum catalysts used in many cells. This story from Physorg.com (my main source of news on this sort of thing) seems to suggest that there are cheaper alternatives.
Micro-electro-mechanical-devices are one of those amazing ideas that makes your mind expand when you consider all the possible applications and ways they could change our lives. Progress is being made in this area as well.
One of the many exciting possibilities of molecular nanotechnology is the suggestion that molecules could be "put together" instead of formed through the normal methods of making useful chemicals. This research from the University of Illinois offers the first glimmerings of this capability using "mechanophores", or mechanically active molecules.