Wolfram Alpha, the "computational knowledge engine" that can help you count your calorie burn, explain confusing once-removed-type relationships, teach you step-by-step maths and otherwise raise your eyebrows just landed in the Android Market.
Is it worth the $US2 being charged? It's a lot better than the $US50 initially charged for the iPhone version (since drastically reduced), and it offers a few benefits over simply hitting up Wolfram Alpha's mobile web page. It's got a specialised keyboard for mathematical input, native voice search, location awareness for pulling up things like geo-specific constellation charts, and likely some local caching to save you time on repetitive searches.
Wolfram|Alpha is a $US2 download in the Android Market; you can scan it and head right to its Market page with the QR code at right.
The Wolfram|Alpha App for Android Has Landed [Wolfram Alpha Blog]