GPS Data logger using MSP430
The MSP430G2231 doesn't have a hardware UART. The best option is to use a timer to clock your bits in and out.

Here's a good example of how to do this:
http://www.msp430launchpad.com/2010/08/half-duplex-software-uart-on-launchpad.html

Wire your GPS to TX, RX and GND on your Launchpad board.

Writing to an SD card is more tricky. SD cards talk a protocol on top of SPI.
I've written a Bus-Pirate-like SPI explorer for the MSP430 which should get you some of the way there:

http://blog.hodgepig.org/2010/09/10/575/

On top of the SPI code you'll also need an SD card driver and a filesystem driver (likely FAT if you want Windows compatability). You could simplify things by writing raw data to the SD card - though this will make it harder to read at the Windows end. Linux could read it with dd.