This is the preferred approach by those who would cringe at the idea of directly approaching a company to inquire about employment. It allows you to comfortably ask about employment without directly asking. Instead of asking a Hiring Manager about opportunities within her company, you ask a "Who-do-you-know" question, which could lead to one of three results: she doesn't know of anyone (or at least is not willing to give you the information if she does); she is aware of someone else who may have an interest (either within or outside the company); or she may have a direct interest herself.
You will find this to be a much more subtle approach, one that almost anyone can handle comfortably because there is none of the pressure that accompanies presenting yourself directly. If they happen to remark that they might be interested, your "Oh really?" response again takes the pressure off, since they are now coming after you instead of you going after them. Here is a sample script for the indirect approach:
Its low pressure, but it does come at a cost. If you are conducting a nationwide search, be aware that most referrals you will receive back will be local or regional at best. And with some managers, if you do not directly ask about their specific needs, you may never get the desired response.