Drinking beer (environmentally) responsibly:

• bottles are better than cans if made from new materials
  
• cans are better than bottles if they have recycled content
• cans are better than bottles if they're being shipped over long distances (less than an ounce versus 6 ounces)
• fuck green bottles; a lot of towns don't even recycle them (fuck heineken anyway)
• local brews use less energy for transportation

The Best bet:
-TAP! the glasses get washed and reused, the kegs weigh less per ounce, and it tastes way better--if you can afford it.

-Slate