Actually, in this case "Limit" is perfectly accurate. The only result of checking this is that the application must call advertisingTrackingEnabled before using the identifier.

If enabled is NO, then the developer can use the identifier for "frequency capping, conversion events, estimating the number of unique users, security and fraud detection, and debugging". Notice that compliance with these restrictions is almost impossible to determine.

http://developer.apple.com/library/ios/#documentation/AdSupp...

Ugh, I hate these. Instead of disabling it at the OS level, where they should do it; they create a "let's give unethical companies another bit of information" option.