Sooner or later, we all face the Dodgeball truth. This comes at the moment when you realize that one of life's possibilities -- a product, an adventure, an offer, an idea -- is really meant for people younger than you.

This bitter revelation is named for the relatively new Web-based service Dodgeball.com. This is a social networking site, and it represents most of what is supposed to be advanced and exciting about the current wave of "Web 2.0" offerings. Dodgeball's goal is to help you figure out, at any moment of the day or night, whether your friends or people who might be friendly are nearby. Toward this end, users construct networks of contacts -- you list your friends, they list theirs, and on it goes -- and lists of "crushes," people they'd like to get to know. Then, with your cell phone or PDA, you send Dodgeball a text message saying that you've arrived at a particular bar or Starbucks or museum. Dodgeball messages you back with a list of people in your network who are within brief walking distance of your location -- and tells them, and your crushes, where you are.