This year's word of the year in the Oxford English Dictionary - hypermiling - is in good company. It seems that many of the words being added to dictionaries lately are green words. Nearly all of the words that hypermiling beat out for the honor, as well as its word of the year predecessors, had an environmental theme.
Hypermiling's official definition is now the "attempt to maximize gas mileage by making fuel-conserving adjustments to one’s car and one’s driving techniques." This includes anything from inflating your tires fully and coasting in neutral, to somewhat dangerous maneuvers, like riding in the draft of larger vehicles.
Hypermiling was up against these words:
Frugalista — a person who leads a frugal lifestyle, but stays fashionable and healthy by swapping clothes, buying second-hand, growing own produce, etc.
Rewilding — the process of returning an area to its original wild state/flora/fauna etc.
CarrotMob — a flashmob type of gathering, in which people are invited via the Net to all support and reward a local small ethical business such as a shop or café by all patronizing it at the same time. Also as noun, carrotmobbing.
Staycation — A vacation taken at or near one’s home, taking day trips, etc.
Hypermiling is also in good company within the OED. Last year's word of the year was "locavore" (which beat out "tase" and "cougar," amusingly) and 2006's was "carbon neutral." There are already some great contenders for next year's word - "carborexic" or "locasexual," perhaps?