Good question. But is it the most important?

Is Arnie really green?

To the one you pose, personally my answer would have to be 'no', not 'really'. But matters of green are pretty broad in scope, and can seldom be viewed in just black and white.

As you point out, at least he is doing something, which in comparison to others is a heck of a lot better than nothing. Or is it?

Because we have the message, and then we have the messenger. As Janet Street Porter pointed out a few days ago, few can be unaware of global warming by now, so do we really need more awareness from celebrity politicians, green-tinged celebrities and the remoras of the media that follow, share and bask in their gre-e-lite (pronounced 'leet) movements and issue forth their pronouncements of what should be done, if not by them, as such? Maybe a bit more back-room deal-making with the power-brokers would help a tad more?

There is also the small matter of gesture politics not actually serving the one thing that matters, which is enviroROI - simply, will what gets done save more carbon emissions than they cause? Financial ROI is another consideration of course, and one for those rich enough to indulge in if they can and wish to. Frankly if you can afford to go green and it does good, then I say go for it.

However, lobbing up to 'sell' such an effort in a hydrogen powered Humvee (or aspiring to a similarly-configured BMW as is apparently the case with Stuart Rose of M&S) to me helps not one jot. For a start, much as I appreciate the potential of hydrogen, its production and distribution currently means that such a vehicle may make the owner look green, but certainly is not helping Mother Earth. And... a Humvee? Why not just get Chris Eubank on the horn and convert his truck? The first message we get is that it is better (only better, mind, as creation and use does still extract an e-cost) than fossil fuels, hence we must therefore use the biggest, most fuel-inefficient-for-purpose lump of tin to consume it?

I agree with him on one point. Making things about guilt, fine or fear have not, and will not work. We need incentive-based initiatives with which the consumer will willingly engage through a perception (hopefully genuinely delivered) of end-benefit an/or reward. And a little bit of leadership by example wouldn't go amiss to get that across.

Sadly, by talking down to us from a Green Tower (I'm still trying to rationalise "[not] powering my private airplanes (plural!),” with “It's too bad for us that we can't live the lives of Buddhist monks (I guess they just go skiing on RyanAir)") I fear such as Arnie et Al (make sure y'all come to see me and my best bud Madge at Live Earth!) may not be the ideal choices to motivate the masses.

Governator aims to make green issues 'sexy'

Yes, he is 'on the cover of Newsweek as one of the big environmentalists'. Maybe that is more for that publication, and other media who publish eco-hype without thinking, to answer. And not only in America.