In February 2006, Google integrated real-time chat into the Gmail email service. The new feature adds a "Sign into AIM" button from the drop down menu of the Gmail page. Once you've entered your AIM log-in information, your AIM contacts will appear among your Gmail contacts, and you can select an AIM contact and chat with them directly.
This is rolling out in the newest English version of Gmail first and will be available in other languages soon. For more information or to start chatting, log in to Gmail at www.gmail.com.