Good question Brian. I'll answer this briefly and try to get back to the subject after I get back from a meeting I have to be at shortly (sorry about that!).
There are lots of ways to define this new field, but one relatively simple definition is using design and management practices that factor in environmental issues along with traditional considerations of cost, manufacturability, quality, and time to , market. Green engineering goes beyond the traditional engineer's perspective and looks at a product in the following ways;
1) What resources (materials, energy, processes, etc..) are consumed when a product is produced? 2) What kinds of wastes, byproducts, and toxics are emitted during it's manufacture? 3) What kinds of resources (materials, energy, environment)does the product consume while it is doing its job out in the world 4) When the product's life is over, how is it either re-used, recylced, or disposed of?
The concept of looking at all four phases of a product's life is often reffered to as "product stewardship."
While this seems like a very broad charter that could be difficult to address, it actually turns out that companies who start looking at these questions actually find themselves becoming more efficient and more profitable. Hopefully, we can address some of the specifics later when I get back.