With a lot of issues, no one seems to care too much until they can actually measure some results that are just god-awful. For example, the fact that there are about 500 million computers in need of recycling in America doesn't really bother anyone too much, because they are all spread out. But if we had a big pile of them (maybe just 1 million) in one place, then that would be a big problem. Just look at my tire fire here and you will instantly see the similarity. We have million of tires in America too, but they aren't really a problem until you put a lot of them in one place and they catch fire.
For green computing, I'm betting that data centers will be the tire fires of the IT world. First of all, they are being constructed like mad, mostly in the Northwest where there is lots of cheap hydroelectric power (there are other good places too.). Now, with a data center, what you are doing in putting a lot of computers in one place, so of course your monthly utility bills are about the cost of putting a elephant in orbit around the moon, every month. Not only that, but these centers are ususally mission critical, meaning they have to be up all of the time.
The second big trend is that companies are consolidating their data center to save money, particularly money related to real estate. Look at HP's new worldwide iniative to consolidate 85 data centers around to world into six, saving about a billion per year. So now we have set the stage for crisis - lots of mission critical stuff in one place, all of which needs a lot of juice to keep it up and running 24/7. Add to that the fact that companies spent millions already consolidating their operations.
Now all we need is for someone to strike a match. How about the U.S. Government, who is not only drafting legislation to look at power consumption in data centers, but has also authorized the EPA to come up with a server efficiency standard. They are starting with servers now, but storage equipment won't be far behind.
All of this suggests to me that there could be some very rapid changes in data center design, server design and power usage. Woe be the IT manager trying to run P4 processors in downtown Manhattan on 10,000 servers, you might be in for quite a ride, particularly when you think that the really big players are scarfing up all the best sites (and energy) right now. And when the government tells you to shut down your mission critical data center because its not efficient enough, that could flatline your business.