Many professional accesspoints like the ones Cisco provide can not only detect rogue accesspoints through the management engines they're connected to - they can actually prevent anyone from using them by attacking them with disassociation packets and whatnot. And of course, report found rogue access points immediately and depending on the number of valid access points in the area - do a somewhat useful location detection as well.
If they're already using a supported wireless solution, which by your mention of the amount of offices, I'd guess they do - it would just be a matter of turning the option on.
The radio monitoring feature uses the radio measurement capabilities on Cisco IOS APs and Cisco Client Adapters to discover any new 802.11 APs that are transmitting beacons. Both clients and APs periodically scan for other 802.11 beacon frames on all channels. Reports of detected beacons are returned to the Radio Manager, which validates these beacons against a list of APs known to be authorized to provide wireless access. A newly discovered AP that cannot be identified as a known authorized AP generates an administrator alert.