Wolfram|Alpha.

Wolfram Research is planning on launch its Wolfram|Alpha in May. If it’s real (and I have some small doubt that it can truly work as planned), it could change the way we interact with the Web, find information, and experience ideas online. Wolfram|Alpha is a computational tool that can answer natural language questions by digging deeply into the known informational universe and provide meaningful answers. Computation over lookup is its model.
Nova Spivack has a detailed description of it but, in a nutshell, here’s what he says Wolfram|Alpha is:

Where Google is a system for FINDING things that we as a civilization collectively publish, Wolfram Alpha is for COMPUTING answers to questions about what we as a civilization collectively know. It’s the next step in the distribution of knowledge and intelligence around the world — a new leap in the intelligence of our collective “Global Brain.” And like any big next-step, Wolfram Alpha works in a new way — it computes answers instead of just looking them up.

Spivack, who got a tour of the system recently, also says the following:

One of the most surprising aspects of this project is that Wolfram has been able to keep it secret for so long. I say this because it is a monumental effort (and achievement) and almost absurdly ambitious. The project involves more than a hundred people working in stealth to create a vast system of reusable, computable knowledge, from terabytes of raw data, statistics, algorithms, data feeds, and expertise. But he appears to have done it, and kept it quiet for a long time while it was being developed.

It appears that Wolfram|Alpha is a perfect compliment to Google’s search tool and a more trustworthy friend of the Semantic Web. Although it’s billed as a computational model, this new product/service may offer a more reasoned and humane approach to Google’s in that it allows a the praxis of questioning the logic of conclusions. It would be nice, for instance to be able to ask “When do most economists predict an end to the current credit crisis?” and get an answer based on a set of real, if biased, known data. I’m eager to find out more.
UPDATE: I tried out its competitor, [true knowledge] (what is it with the extra characters in these new systems?) by asking the following questions and receiving the following XML responses:
How many stars are in the milky way?

completeness unknown
100,000,000,000

How big is eifel tower? [purposely mis-written]

completeness unknown
324 Meters (1,062.99 feet)