From ICANN's blog entry, "This is advance notice that there is a scheduled change to the IP address for one of the authorities listed for the DNS root zone. The change is to L.ROOT-SERVERS.NET, which is administered by ICANN.The new IPv4 address for this authority is 22.214.171.124.
This change is anticipated to be implemented in the root zone on 1 November 2007, however the new address is operational now. It will replace the previous IP address of 126.96.36.199."
While this won't cause any failure of DNS, such migration is usually an interesting one - with some 'retired' IP addresses still receiving DNS queries some 10 years after retirement. There are a number of root DNS servers - and most DNS server software will ask any root server it can for a list of current root DNS servers and then use them. It's always nice to update your root.hints file however. You can do this using: "dig @a.root-servers.net . ns > db.root" (and move/substitute db.root for the correct file/location on your system).