@Aimee Lawrence @Adam Eaton Here is a link to the city gov site with the most up to date information http://www.fcgov.com/shorttermrentals/
This is a situation in which the devil really is in the details. For example, I have some friends who are VRBO'ing their place close to Old Town and netting about $6K/month. Fortunately for them, for whatever reason, their neighborhood is excluded from the more restrictive regulations and they're rental operation won't be affected. Elsewhere however, regulators are going to clamp down and it'll be pretty easy to find anyone trying to bend the rules, i.e. via simply searching the most popular listing sites like AirBnB, HomeAway, and VRBO.
Also, property management companies OUGHT to be a good resource for the latest rules and regs, but make sure you consult someone who knows their ****, which is usually clear after a brief phone call. If you do put management in place, the fees are higher than on a SFR, around 20-25% based on conversations I've had. It's not a bad option to consider though given the hands-on requirement of a short term rental, e.g. expectation of quick communication with renters, frequent turn around of units, etc.
Good luck!