I completely rewrote my resume a couple of years back, having been a contractor for (then) a couple of years. The main thing that I removed from it, that I think makes a contractor CV completely different from a permanent CV, was the chronological career history.
The key question that your CV needs to answer changes when you switch from permanent to contract, from this:
"is this person a good fit for our organisation and the role we have on offer?"
"can this person provide the service that we need?"
It's that second question that makes a chronological history of work experience less than optimal because you need to show that you can provide the specific service that your client is looking for. It may well be that you provided a very similar service 3 contracts previously. Does that make it any less relevant? Absolutely not, and that role needs to be more prominent on your CV than halfway down the second page.
Because I am a software developer, the first thing on my CV, after a short summary, is the key skills that I have, from programming languages through to systems and processes. So far so good and then same as my permanent CV. Next I go through a number of key projects, presented in whichever order I choose so that they are tailored for the role I am applying for. The detail of each project includes the client name and length of contract, but not the dates, so that I can move them around as necessary. The style I use to write each project description is in terms of the problem that I was hired to solve and the solution that I was involved with providing. After the key projects I include the career history in a single list that is just made up of organisation name and dates but no other details.
I tend not to include anything that is not relevant to the skills and experience that I can offer to the client that I am potentially working with. Given that the CV is still the defacto mechanism that changes hands when you are targeting an assignment, I wouldn't say there was ever a situation in which you could "get away" without having one. You could change things around slightly and have an online CV/portfolio on your website or one of the career building websites (Stack Overflow Careers anyone?) but it's still a CV, albeit in electronic form.