I think the blacklisting should be commented out http://learn.adafruit.c...

I think the code might be the wrong way round. We should be commenting out the blacklisting of the modules as per:
http://learn.adafruit.com/adafruits-raspberry-pi-lesson-4-gpio-setup/configuring-i2c
rather than uncommenting them (and therefore stopping them from loading). Admittedly the source document was not that clear on this (as a logo gets in the way and makes it tricky to read):

http://www.recantha.co.uk/blog/?p=2582

Step2:

Next SPI and I2C is “blacklisted” (i.e. turned off) from modprobe (the module loader) by default. Edit /etc/modprobe.d/raspi-blacklist.conf with vi or nano and comment out (place # as first character on line):
blacklist i2c-bcm2708

The script currently uncomments the blacklisted modules (I think having played with it).