TeamTalk helps your team to communicate better. It brings to SharePoint a quick and easy ways for people to communicate their status to others.
The left of the screen contains a scrolling list of status messages from your team. The box in the top right allows anyone to send a message of no more that 140 characters, and the section below it displays any messages where you are mentioned.
By including #Hashtags in your messages, you can group similar status messages together by topic, and with Version 3.0 you can even subscribe to them.