I am currently in grad school in the UK in the area of computer science. Our phd model is as follows:
Year One: Intro, get your head around things
Year TWO: Work
Year three: Work
Year four: Writeup

The topic, etc are all up to you ... very much a "sink or swim" approach. People get around by forming peer review groups and generally talking to one another/others...

I was wondering what other models out there exist?