Unless you have MAD skills &/or INSANE experience, you will not get an interview at Rackspace without an inside referral. Why? Everyone wants to work here (and they should), and we get too many applicants for every position to look at each one. Rackspace relies on the amazing staff they have in place to help them pare down the pool. Inside referrals mean a lot - when a Racker refers you, they are putting their reputation & their "brand" on the line, and we don't do that lightly. HR knows this, and takes Racker referrals seriously.
That being said. Step 1: Phone screen with HR. If you make it past that, welcome to the interview!
Interview: Three panels, one hour each, each with a specific focus. You will be interviewed by your potential future colleagues as well as your potential future boss, and their opinion carries as much or more weight than the supervisor's. For some roles in which you would be part of a small team or pair, one person's veto will kill you, regardless of what anyone else thinks.
Be yourself, be real. Stuffed answers won't work here. You may be interviewed by people in flip flops & do-rags (I was), but you'd best be in a real suit if you want to have a shot. I won't give away what types of questions to expect, but like any interview, know the business, know the major players, know what your role would be expected to do, and plan to tie in your experience with the job description. My interview experience was by far the best I've ever had with any company. I left feeling like even if I didn't get the job, I had an awesome conversation with some really great people. Best advice - BRING your personality. And if you don't like kooky, off-the-wall, creative, different, fly-by-the-seat-of-your-pants, let's-go-change-the-world, it-doesn't-exist-so-let's-create-it . . .. don't apply. You're signing up for a crazy, wonderful life, not just a job. All in, or stay home.