Typically, management consulting firms specializing in strategy work use case-style interviewing. This has the benefit of offering candidates a sense of the type of work that they will do, while allowing the employer to assess the candidates. However, case interviewing can be used by any employer who is looking for strong problem-solving ability. Below are some hints about preparing and succeeding in such an interview, coupled with examples of real companies that use the case study interview.
From the Job Employment Guide--Case Study Interview
A selection of companies that conduct case interviews from Quintessential Careers
Companies Using the Case Study Interview Method: Examples and Hints.