The new leed exam, released in 2009, is for building professionals to gain accreditation as an expert in environmental responsibility.  There are two parts to the exam, Tier I and Tier II.  You can become a Green Associate by passing Tier I, which indicates a basic knowledge of environmentally sound building design, construction, and operation.  Tier II gives you certification as an Accredited Professional in one of several fields.  Each test has 100 multiple-choice questions.  It costs $50 to register and $200-250 to take the exam.  There are many resources available on the Internet to help you to prepare for the exam.