Hackable bug found in net's heart

[Tux]

The net's basic plumbing has a leak.
One of the net's central technologies [TCP] has a serious security vulnerability warn UK and US infrastructure protection agencies.

http://news.bbc.co.uk/1/hi/technology/3646223.stm

The BBC article isn't very detailed but the bug seems to have massive potential for serious havoc.
How easy would it be to change the implememntation of TCP? A mammoth task by the looks of it (have they done it before?)

[Void Main]

Yeah:

http://www.us-cert.gov/cas/techalerts/TA04-111A.html

:(