I'm not sure I understand what Wolfram|Alpha is yet, but so far it's pretty impressive.  Developed by Stephen Wolfram and his team, it claims to be a "computational knowledge engine".  The input box looks like a search engine, but it is definitely NOT a search engine.

When you type in a question, it attempts to show you all of the relevant data it can find.  It is actually calculating and charting this information real-time in order to present it to you.  Because its built on top of the Mathematica Engine, it can also handle math problems.

I think this will be an important tool for many designers of infographics, because you can get some of your raw data directly from Wolfram|Alpha.  As they add more data into the system over time, this will become one of your best resources for information.  They have a pretty extensive page of examples by category that is a great place to start.  Also watch the short video by Stephen Wolfram showing what the system can do.