Cheers, I'm not doing it with my Nikon DSLR. Bought a cheap second hand Canon P&S. Made sure I got one which can be hacked. So yeah hacked it (using the CHDK). This enables you to load scripts onto the camera. There are all kinds of scripts. Im using one of the time-lapse scripts to do the time-lapses. You enter some parameters (like how many pics per hour you want it to take) and then start the script and leave the camera
ps It's also known as an "Intervalometer" - some camera's even have it built in apparently!