Wolfram Alpha [$49.00 - iTunes link] for iPhone (and iPod touch) is the "computational knowledge engine" made mobile. While the website is (currently?) free, the iPhone app is decidedly not. But is it worth the premium price? Christian Warren from Mashable says:
It’s a high end graphing calculator (that supports discrete number theory, Calculus derivative and plotting of functions), an almanac, a currency/unit converter and a pretty sophisticated stock analysis tool. And that’s just the beginning.
She shows several examples of the kind of results the Wolfram Alpha app produces, and is particularly impressed with its mortgage calculations and graphical math calculations.
So, for students or those who work in fields that require these specific types of computational features, and Mr. Spock, it very well could be. If anyone tried it out, let us know what you think!