Is there an info.plist key for advertising identifier use

There is an entry for itsappusesnonexemptencryption (ITSAppUsesNonExemptEncryption export compliance while internal testing?), but is there one for the Advertising identifier, and if so, what is it?

No, there is nothing in the info.plist that's related to Advertising Identifier.

When you will submit the app to the App Store you'll need to check some things in order to inform Apple you are doing usage with the identifier. More details regarding that here:

https://developer.apple.com/library/ios/documentation/LanguagesUtilities/Conceptual/iTunesConnect_Guide/Chapters/SubmittingTheApp.html

Here is how to retrieve the Advertising Identifier:

Objective C -

@import AdSupport;

...

NSString *adId = [[[ASIdentifierManager sharedManager] advertisingIdentifier] UUIDString];

Swift -

import AdSupport

...

let myIDFA: String?
    // Check if Advertising Tracking is Enabled
    if ASIdentifierManager.shared().isAdvertisingTrackingEnabled {
        // Set the IDFA
        myIDFA = ASIdentifierManager.shared().advertisingIdentifier.uuidString
    } else {
        myIDFA = nil
    }

(updated to Swift 3.0)