Am I reading that right? They're dropping from 10GB free outbound transfer to 1GB?
http://googleappengine.blogspot.com/2009/02/new-grow-your-ap...
The AppEngine team says they chose the quotas so 90% are free, so majority will not be affected. There are over 80,000 applications, so if even 1% of them are exceeding existing quotas, that's still 800 apps that are affected.
This change will affect everyone that actually uses GAE free hosting, even the ones using much less than 1gb/day. The way the free quota works, it's throttled to keep you from using it up all at once -- which means that anyone without billing turned on just took a massive hit to QOS.