Presumably it's the same one I got Dizzy, and it's aimed at President Bush, and campaigning for changes in the American drink driving laws. So it won't have any effect on the laws here.
Have been on a few sites and can't find any reference to a similar email campaign in the UK, which is what we need to have any effect (if possible) on our own laws.
Even the UK
Campaign Against Drunk Drivers doesn't mention one.
These Email campaigns need to be circulated, and rely on getting to the end of the chain and the final recipient delivering the petition to the correct postal address.
I personally think it would be far better for for any petitions to be done on paper, and maybe contacting the people at the above link would be a starting point for advice and info on doing so if you were interested.