Although reading the advisory linked from the article body will give you most or all need to proceed ("CERT is your friend"), here are some important hightlights (also adressing some other posters requests for more information):
The ISC has released BIND versions 4.9.8 and 8.2.3 to address these security issues. The CERT/CC recommends that users of BIND 4.9.x or 8.2.x upgrade to BIND 4.9.8, BIND 8.2.3, or BIND 9.1.
Because BIND 4 is no longer actively maintained, the ISC recommends that users affected by this vulnerability upgrade to either BIND 8.2.3 or BIND 9.1. Upgrading to one of these versions will also provide functionality enhancements that are not related to security.
More info on the problems:
This page at the Internet Software Consortium (the maintainers of BIND) has a more information about the BIND's security problems and their severity than you want to know.
This CERT advisory was issued in collaboration with
Network Associates'Covert Labs. Their advisory has a deeper analisys on BIND's problems.
Evolution doesn't take prisoners