The price of computer hardware really has dropped significantly in recent years, and there are few representations more obvious than the Raspberry Pi: that single-board PC which is about the size of a credit card and uses an SD card as storage. It seems a bit mad, being able to retail for $25 or so.
If that's mad then the Stellaris Launchpad must be insane, since it is the same concept for $13 a go. It relies on ARM hardware and at the price you could buy them as Christmas gifts for all your friends.
The Launchpad isn't entirely similar to the Raspberry Pi, for the two use different circuit boards and therefore will have different functionality. Tutorials and explanations for doing things with a Launchpad are appearing on the Texas Instruments wiki already, so jumping in without experience shouldn't be too bad.
The Raspberry Pi seemingly can be used as a complete computing setup with ethernet, a keyboard, and all the rest, but the Stellaris Launchpad likely could not. Then again, the Raspberry Pi doesn't have the backing of Texas Instruments, the manufacturers of the TI-83 and TI-84 calculators - which are more expensive than their single-board computer.