It seems that recent versions of php (5.3 and above?) the sqlite driver for pdo is not installed/enabled by default. This, despite official claims to the contrary.
Although there appears to be an easy fix for linux/debian/ubuntu users thanks to apt-get
I'm having trouble fixing this on OSX (I think ampps works OK, but that lacks other extensions I need, and mac ports doesn't work). Anyone have a fix for this? (failing that, more info?)