as already said max 2 pages, tailored for each job, easy to read and relevant and use the correct current job terms/buzz words to describe your skills so the software if computer read highlights your CV as relevant.

I keep seperately a full CV for every job and skill which i use to cut and paste to do tailored CV's. Also its useful for later stages in the interview process if your going for complicated/executive/management roles where often they want to get into the nitty gritty. Mine is all encompassed in an A4 ringbinder as a "personal development folder" which is a armed forces thing to sell armed forces people to the civilian world.