I recently was looking for a way to get data from one Gdocs spreadsheet to another one. I had been puttering with it for a few minutes and was about to call it a night (it is 4AM after all) when I realized "Hey I should try searching for the answer".
Sure enough, a quick google search kicked up the magic command to do it.
It turns out there is an "ImportRange" command that does exactly that. In my case I wanted a particular cell, but obviously, it does ranges of cells too.
You will need the spreadsheet key, which you can get from the URL. The only other trick is the arguments needs to be in quotes, or you will get an error. You also need to have permission to view the spreadsheet.
The google docs help is really good. If you get stuck, give searching a shot. It shouldn't come as any surprise, it is google after all. Their search is pretty good. :)