Let me know how it goes. I am planning on also buying a raspberry when I have some free time.
Got it working with the tutorial you posted. You do need a 4GB card minimum because node will fill up the 2GB card.
(http://blog.rueedlinger.ch/2013/03/raspberry-pi-and-nodejs-basic-setup/)
I'll report back if I encounter any problems. Have it set up with a smaal mtGox account. Tweaked the settings and with some manual backtesting so hope it works
Edit:
Dont forget to do make a screen so it wont stop when you logout from ssh.
> sudo apt-get install screen
> screen -S gekko