So who owns the radio wave airspace above your land?

This article talks about a baseball park that's mad about an office complex that has a WiFi Access point. That's not what's interesting. The Office building's WiFi connection can be used from within the baseball park, and lots of people are doing it.

So the question of the week is, does the baseball park have any legal basis to stop the office complex's WiFi from drifting into thier land? Something like this could feasibly end up in court -- imagine if the baseball park wanted to have WiFi and charge for it, but the office park next door had their's open for free?

I personally think that the radio space is not part of the ownership of the land, but I could definitely see the court system thinking otherwise -- of course then radio stations might get screwed too, and where would it end? I bet there's some legal precedent about this with standard AM or FM broadcasts.