What does it not do? I just ran across this iphone app on Mashable and it's look like having a genuis in your pocket! Based on what I can gather from website the application utilizing it's proprieatry "Computational™ Knowledge Engine" it operates as a REST-style webservice and can be used with any programming language that supports HTTP and XML. This means that the most popular web languages can all interact with WolframAlpha’s base system to bring up results and customized readings.
"Drawing on 20+ years of development, 50,000+ built-in algorithms, and 10+ trillion pieces of continually updated and curated data, the Wolfram|Alpha app is the ultimate replacement for almost any kind of calculator or reference book—and much more.
The breakthrough technology of Wolfram|Alpha for the first time lets you get expert-level answers to your specific freeform questions—complete with stunning, dynamically generated visualizations and tables, and richer and deeper information than you imagined possible."
Go check it out for yourself: