Well the carriers won't be able to say they can't monitor QoS easily, after this announcement.
Without question, QoS is the single most important factor in winning the conversion from PSTN to IP based telephony services, especially for business grade calls.
If people have a hard time dealing with lousy cell service, that is not a reason to think that a regular call from an office to a customer, colleague or business associate can suffer the same horrible fate.
VONAGE does not offer at the present time any QoS guarantee. I suspect AT&T does to their enterprise customers and look forward to finding out. This tool will make it easier, for the carriers who don't have their own.