Simon,
However, the AT&T thing looks like a combination of Arbor PeakFlow:DoS for automated DoS detection on the network, and what used to be Riverhead (and now acquired by Cisco) for "traffic scrubbing" to allow normal traffic to continue to be passed to nodes under attack.
COLT have been doing this exact same thing in the UK for a while now.
We have been doing it *globally* for over a year now, using Arbor Peakflow DDOS and Riverhead Guard, [both of which are excellent products from excellent vendors [take note Cisco!]]. http://www.nanog.org/mtg-0306/afek.html is the presentation Nico gave at SLC. http://www.techweb.com/wire/story/TWB20040428S0006 Guess which site was on the COLT network. We've also protected a large number of our customers against the blackmailing pay us 10K or we'll DDOS you type situations, although few want to press release that type of situation :-) Regards, Neil.