I think the gas tax is politically impossible with the Bush administration in office for another 2½ years and especially before the dire nature of the current crisis is really apparent.  It is very unlikely that a venture capitalist would want to take that bitter pill to the current powers that be.  

I think he would want to champion some technical fix, something for which people will think he has some credibility.  Something like Robert's biodiesel from algae or wind power.  He might be willing to champion a new generation of nuclear power plants that will inevitably be a big part of our mitigation but which is still pretty politically radioactive.  Or possibly put money into developing new battery or fuel cell technology.

A gas tax is needed which is engineered to ensure that regardless of the underlying cost of crude, the price to the consumer will steadily increase.  This would provide the predictability required to spur investment in alternatives, and a permanent change in attitudes to consumption.  Revenue raised can be used to mitigate the effects of rising prices on vurnable sections of the community.

How to make it politically acceptable - that is the real challenge.

A better way to frame the debate would be to relentlessly pursue the huge disproportion between government support for fossil fuel industries vs. alternative energy industries. Have you seen the chart of newly installed wind power capacity in the US (somewhere at awea.org)? It looks like a roller-coaster because there is a tax credit for wind power which has to be renewed by Congress every 2 years. Consequently, no-one installs new capacity in the "renewal years" since they don't know if they'll get the tax credit. That's insane! The tax credit should be extended to at least 5 years so that the environment becomes a bit stable - the Spanish model of a minimum rate at which utilities must buy renewable power might also work. It sure does work for Spain.

In short, the general public is starting to realize that renewables will be crucial in energy independence. This realization can and should be leveraged to adress the imbalances in government support for various energy industries. Shifting support from Big Oil to renewables can be presented as a revenue-neutral and labor-market-neutral policy that is very hard to refute. Another angle is that it's a fitting "punishment" for Big Oil's "excess profits".

Do you have anything like the UK Annual 'road fund licence'? Basically a tax on the vehicle itself.

This could be linked to engine capacity / mpg / carbon emissions. The bigger the engine etc , the higher the tax.

This has started to happen in the UK , but with minimal effect yet as the difference is not that great in tax rates and if you can afford a large 4wd, you can afford the tax difference.

One side effect however is that it bites impoverished hill farmers who need land rovers more than it bites a 'Chelsea Tractor' driver.

I can talk from my experience here in Argentina (and I know that's like comparing pigs to bicycles).

Gas has always had an important tax here, in fact every fossil fuel.

Today, %60 of what you pay for filling up your tank is gas tax. I think this follows the general pattern in Europe.

We  "achieved energy independence"  more than 15 years ago and today Argentina is a mild oil exporter and our cars are small just like the Europeans.
That's a different pattern of what you could see in México or Venezuela (comparing apples to apples this time) where, as far as I know, gas taxes are not so high and cars are bigger and not so efficient.

Of course, timing issues regarding the USA case can not be ignored.

Regarding the "efficiency and rationality" of markets, the idea of having your A/C on while you're not at home, driving thousands of miles each month to get to your work, using SUVs to get to the grocery store around the corner, are IMHO very wasteful behaviors. This has been known for years in Europe, where energy taxes have played an important role.

Best

Fernando