I got a phone screening (very basic questions). 1 week later I got a non technical phone interview. 1 week after that, technical phone interview. Several days later I got a technical interview. Data structures, design patters, and database theory. Several days later I got an on-site interview. Interviewed by two engineers with 5 to 8 years of experience. Focused on language specifics. Rate yourself on language X. Then, asked some obscure question on language usage. What's the most complicated task you have completed with language X. Asked about formal definitions of closures, class functions, polymorphism. Asked to design a solution to integrate various independent business within the company. Asked what type of role you see yourself in (from what I could tell the company does not have systems engineers, data modeling specialists, etc. they are all software engineers with various levels of responsibilities. Some are entry level, domain owners (control all aspects of a subsystem), senior developers.) Then interviewed by three senior level developers. Asked to do data modeling. (Advice - study data modeling patterns and when to apply them). Asked about design patterns. Implement singleton pattern. Asked critical thinking questions (see programming interviews exposed book). Interviewed by senior management / human resources. Where do you see yourself in 5 years? Why rackspace? Rackspace is a big company, you have only worked at small companies, what kind of culture shock do you expect?
General Advice:
brush up on language specifics: closures, design patterns, language trivia
brush up on data modeling
read programming interviews exposed