Professional CV vs. LinkedIn Profile
Social media has always been a big part of the job interview process, even before the rise of the Internet. Your professional resume is a form of professional media, but with the rise of the LinkedIn profile, there is definitely another route to take if you are looking for a job.
Even though you can place yourself online in 1000 different places, a professional CV will never lose its relevance. Even if you put your CV online, you have much more control over that then you would over a public media profile. You can easily update your online CV, and you can also direct different job opportunities towards different versions of your CVs online (to fit the exact position(s) that you are looking for).
However, not to use LinkedIn would be remiss of anyone who is seriously looking for a job. As the network is dedicated to business social networking, it instantly connects you with people in your industry and people from your past that might be able to help you.
This does not mean that your LinkedIn profile will be the end-all be-all of your job search and that you can simply put up a resume there and forget about the rest of the work. As LinkedIn is a B2B website (for the most part, especially in terms of job networking), most of the people who are there are looking for work or networking. It is actually quite hard to find an employer, so imagine how difficult it must be for them to find you.
However, your chances go up if you use both online venues to promote yourself and combine that with the legwork that will never go out of style no matter how many different online formats the world can come up with for self-promotion.