Any HR person will tout their knowledge and specific expertise when interviewing. However, it takes a true professional to discover, investigate, and evolve an environment one has no experience in. In today's market we must learn and grasp new and emerging industries.

How do we acquire Business Acumen when going into an industry we are unfamiliar with?

The short tips or answers:
1) Use your interviewing skills as a recruiter or HR Talent to investigate, question, and research the industry.
2) Don't be afraid to ask the simple questions like
Where would you go, How does that work, What happens when you push that button, What do you need to know to get a position, or client in that arena? When did you discover this technology. These are the type questions a reporter would inquire about.
3) Ask an expert to explain in common terms how they would describe their particular industry and craft, to the common man or woman. You will be amazed at how complex technologies, and industries make sense.
4) Ask HR folks or Clients and Vendors of that company and in that industry for what differentiates them.
5) MSN, Yahoo, Google, and Ask.com it
6) Wikipedia terms that are unfamiliar
7) Look at papers from college grads on the subject although rough, it helps.
8) Don't research any industry that you wouldn't be interested in--but do find out supporting industries that you may be interested in, and see if there is a tie.
9) Go for it, nothing is gained by sitting on the sidelines.

Then go from there, learn as much as you can repeat with confidence.