How can Gravity Forms be used for vacation rental websites, other booking form solutions?

I would think if you couple Gravity forms with a Wordpress Custom Post Type (CPT), you could achieve this quite easily. That way Gravity does all the tricky form stuff like validating user input etc then you generate a new record for your CPT. For more sophisticated applications, you could also couple it with other plugins for example we've just finished using Gravity Forms as the front-end to a conference room booking solution we build for a customer. Gravity will pop a credit card form if the person booking is a visitor or not if they are a current logged in user. We then populate the calendar booking with Gravity's form entry.