I just went through this and a google search will yield lots of great articles on this subject. What I learned that in my case and I bleive its true for most if you rent more than few weeks a year, was that in the US your regular homeowners insurance likely will NOT cover injury or damage relating to operating short term vacation rental business.
I was pleased to find that the coverage was not that much more expensive than tranditional "Condo/Renters" insurance but I would check with your insurace agent. There seems to only be a few insurance companies covering this market.
I am renting a condo that I rent time and dont' live anywhere near it. Your situation might be different!
Andrew