First part was the phone interview.
Know your basic AD functions, TCP ports, DNS, Windows Web hosting essentials, MSSQL essentials (ports, files, extensions, administrator usernames).
Second part was the break fix scenario, you will be monitored for how useful you are at searching for information as the test is an open book test. This picks up and adds more things from the phone interview, think of the phone interview as a table of contents of all things to come after the phone interview.
Third part of the process is face to face interviews with members of the team and managers.
Members of the team will test you on all topics discussed on the phone interview.
Be ready to explain your butt off. If you want to make good money, know more than the essentials, know all there is about all topics covered on the phone interview:
DNS
AD (FSMO roles, functions)
Server Roles
MSSQL
Ports
Terminal Servers
Networking (ports, NAT, sub-netting, Firewalls, static routes, VPN)
Clustering
Storage (HBA, SAN, DAS, NAS, RAID)
The Manager's interview process like others have said is to see how you will fit with the team and how your customer service is.
Overall, if you are a system administrator or are familiar with the tools in your day to day, it is a piece of cake, study all you can, and you can land a high position. If, however you are new to this, study the best you can, practice what you can and you will land at least a level 1 position.
Connect with everyone and you will get a call back!
Also, customer service needs to be top notch, as Rackspace looks for "Fanatical Support" candidates.
If you have the customer service skills, they will teach you as long as you are honest and know the basics of a system administrator.
