What the heck is Wolfram Alpha anyway?

The Internet seems to be abuzz with a new "natural language" search engine called WolframAlpha, widely touted as a Google-killer.  But what the heck is it, and how does it work?  More to the point, how much will it cost?

There's a video from WolframAlpha which seeks to explain it...though it looks pretty spiffy, I guess they've chosen topics they know will produce visually arresting output.   Cnet News has a useful article (Wolfram Alpha shows data in a way Google can't) featuring opinion from several users.

The Wolfram Alpha "computational knowledge engine" appears to be online and working. I tried a few searches:

"lifespan" - worked well, with some global statistics.  It prompts you you specify more terms, such as nation.  I was interested to see how lifespan has changed in the 20th century.

"lifespan during 20th century" didn't work; "lifespan 1901-2000" and "lifespan from 1901 to 2000" both produced the result Wolfram|Alpha isn't sure what to do with your input. This was disappointing, since it would seem to me to be ideal meat for a computational knowledge engine. I then moved on to sport.

Wolfram|Alpha wasn't sure what to do with the queries "tour de france winners"or "fastest cyclist".  In fact the latter query elicited the response "I'm sorry Dave, I'm afraid I can't do that..." - apparentlyit had exceeded it maximum test load.

So that was that for the time being.  I suspect the system at launch will be limited by the data sources they've curated  - and since the aim is for computed knowledge, and the data are analysed by mathematics, the output data will relate mostly to numerical data.  The problem is that how comprehensive a result is obtained must depend on what data sources are being analysed, and it's not clear to me how a user can be assured the computation results are either up to date or complete (or indeed independent of any systematic bias introduced by the source data).

I think the official launch is 18th May.  I believe the system will be an interesting addition to internet search capability, but it'll be a specialist addition, and not the Google-killer it's been widely touted as.

For more, see the WolframAlpha FAQs, blog and downloads (includes browser addons).  I added WolframAlpha to the drop-down search engine list in Firefox rather than the toolbar, as my little laptop has a small screen and adding more clutter to the browser isn't helpful!