This seemingly straightforward question accomplishes a number of things. First of all, it's a good check of the ability to keep confidential information secret, as well as an indication of whether a candidate will badmouth a former employer. Second, this question tests the candidate's ability to think broadly and strategically. Like question 1, the content of the answer is less important than the thought process that goes into the answer - unless the best the candidate can come up with is something banal like, "My last employer should have bought better coffee."