I associate two things with web 2.0 - design and functionality.  The design is simple, attractive and easy to find your way around.  Design may also be green in color, but Green in terms of efficiency, cleanliness and conservation for me is closely tied to functionality in web 2.0 development.  Green functionality includes business automation systems that reduce the amount of printed paperwork and shipping api integrations that cut down on the amount of trips back and forth to the Post Office, along with interactive visualization software that practically eliminates the need to send out samples along with waste associated with refunds and changes in projects.

Technology provides tons of opportunities for companies to go Green. Another example are e-mailed news letters and blog integration as opposed to sending out regular mail. Let’s also not forget another great aspect about going green with technology - the savings to the bottom line.