Re: [grue] Ok, so what's the legality on this? *Hypothetical B jump*
In practice? You probably won't get busted for it.
In theory? You'd need the permission of the homeowner's association.
Legally, condominium ownership is a bit strange. The way it works is that the individual condo "owners" actually only own what's called an "air lot" or "air parcel" which amounts to the actual space in between the walls of their unit. The actual walls of the unit are owned by the homeowner's association, which is required by it's charter to maintain and keep up those walls (and all the other physical parts of the property, like sidewalks, lawns, hallways, etc). As a result, in actual legal terms, the individual "owner" of the condo does not actually own the balcony you jump off, or the beach you land on and therefore cannot grant permission to you to do the jump.
Note that the above is my personal opinion, based on my understanding of laws specific to a few states. It may not apply in your particular jurisdiction, and in any event I am not a licensed legal professional, so my opinions should not be treated as legal advice. If you want a legal opinion for your particular jurisdiction, I recommend contacting an attorney licensed to practice there. A property law specialist would probably be your best bet.
edit: typo