The Web Analytics Association is asking for public comment on a new and revised standard definitions for metrics regarding visits, content, and conversion. The WAA is hosting a blog where the analytics community may give comment. They will be accepting comment through early 2009. Discussion of the new standards will also take place at the eMetrics Marketing Optimization Summit in Washington, DC October 20-23.
You can access the new and revised definitions here.
An addition to the definitions is an "Ask Your Vendor" denotation, which will provide questions that can be asked of vendors when terms differ among vendors. The WAA is, however, asking vendors to standardize the definitions. The "Ask Your Vendor" denotation is a provision to address confusion in the meantime.