In playing with the limited tool today --- Google is rolling it out in stages, with the first one going back to February, but soon to date back to 2006 --- it offered a great library of data.
The tool shows the velocity of a topic and permits you to isolate a time to explore what was Tweeted.
"All of us are just beginning to understand the many ways real-time information and short-form web content will be useful in the future, and we think being able to make use of historical information is an important part of that," writes Dylan Casey, the product manager for real-time search on Google on the company's official blog.