If you’ve used Mail.app then you’ve seen the little box around phone numbers and addresses occasionally. If you right-click on it then you’ll see something similar to the following:
This is called a Data Detector and is one of the 300 new features that were put into Mac OS X 10.5. The concept of the Data Detector can be extended to include other applications provided they are capable of using them. For example, iChat. iChat does not make use of Data Detectors by default, but you can enable them by running the following command:
defaults write com.apple.iChat EnableDataDetectors 1