While it can't use an external xtal, it still has an internal crystal oscillator which can clock it at some MHz, up 16 MHz I think. It's not as accurate but cheaper and more flexible. I did a port of the Contiki OS to the Launchpad, which now comes with the msp430g2452 (16kB flash/256 B RAM) and the 'g2553 (16/512). At home I have them using cc2500-radios (2$ modules from aliexpress) and a radio duty cycling protocol I wrote, with plenty of flash space left for user applications.

You can find the port at https://github.com/msloth/contiki-launchpad and a write-up at http://www.bithappens.se/blog/2013/05/26/contiki-for-ti-msp4... and http://www.bithappens.se/blog/2013/05/26/simple-yet-efficien... with lots of measurements and other crowd pleasers.

The g2231 etc certainly are not specced to work from high frequency crystals or oscillators, but in actual use it works:

http://forum.43oh.com/topic/594-use-a-12mhz-external-square-...

I was under the impression that the newer chips are able to clock from an external crystal. My 2553 certainly came with one, though I have had no need to use it yet.

That's the crystal for the slow clock, which runs at about 32kHz. You still can't clock the main clock off it.

The launchpad works with any MSP430 that fits in the socket, including smaller chips.