I'll chime in too... In addition to other non-fossil fuel technologies already mentioned, solar (especially solar thermal) should be emphasized. Just doing a back of the envelope number crunching using
Arizona to become 'Persian Gulf' of solar energy - CNN.com as the example:
The $1B solar thermal plant in that article will generate electricity for 70,000 households. Assuming there're roughly 100,000,000 households in US, at that cost it'd take 1,400 * $1B = $1.4 trillion to get all of those households to be switched entirely to solar thermal electricity. Obviously that's oversiplifying things -- not every state is blessed with Arizona's abundance of sun and I believe the $1B cost of this plant includes considerable subsidies. But on the other hand, the economies of scale and improvements in technology would make this approach more affordable per watt if it were to be scaled at national level.
$1.4 trillion is A LOT of money but considering that the Iraq war alone already cost $500B by official estimates and (a lot more by unofficial estimates), I'd say $1.4 trillion spent entirely in US on solar termal and, in parallel, a significant push for plug-in hybrids is not a terribly high price to pay. In addition to making US permanently energy independent it would also partially or completely solve most of our other issues: foreign policy (Russia, Iran, Venezuela, and others will no longer be able to use oil/gas for political leverage), trade deficit/weak dollar (over 30% of trade deficit is due to petroleum imports), inflation (in energy as well as in food -- corn can go back to being a food instead of a fuel), not to mention the climate change! And of course there's no need to immediately replace all of the existing electricity generation with solar thermal -- simply ensuring that all or most of new capacity is solar/renewable and slow phase-out of old fossil-fuel based capacity will make a huge difference.
Again, I don't profess to appreciate all the difficulties involved in putting something like this plan into action but I refuse to believe that they are so great as to make it unworkable. It'd be an effort on par with the Iraq war in terms of costs but with many fewer deaths and many more benefits.