Computerworld article by By Jeremy Kirk November 2, 2009 is reporting:

IDG News Service - The Conficker worm continues to be one of the most prevalent threats facing PCs running Windows, according to a new security report published by Microsoft.

Conficker spreads either by exploiting a vulnerability in the Microsoft Windows Server service, through infected removable media or brute-forcing weak passwords on other PCs.

The worm is still circulating, mainly in enterprises, ... Due to its password-cracking ability, if Conficker gets on one PC in a company, it can often then rapidly spread.

Please see the original article using the link above

Comment by the O.P.:
Corporate systems (ie infrastructures) are just a nightmare to cleanup once an intrusion has occurred. Even if you start cleaning immediately, the infection(s) just come right back and your entire staff will just spin their wheels until an extraordinary measure is taken:

Divide the resources and conquer

When worms replicate using Shares, the reoccurance rate is even faster

The whole network will need to be replicated (just a good idea anyway to have redundant networking).
Then each system can be sanitized by

1. Taking each system off the network
2. scanning and removing the intrusive worm, virus', trojans
3. then once known to be clean, moving the sanitized system to the backup network
4. when all systems are connected to the backup and none are on the primary, the infrastructure can resume normal operations

In addition, the servers must also be sanitized and re-certified even before the clients have any access from the backup network. The DNS, DHCP, Active Director and Exchange Servers will need to be moved and reconfigured to drop all access from the original network and to support only the new / redundant net.

If the staff is very careful in the analysis and take good notes as to how to disable the infection, it is possible to automate the cleanup rather than brute force scan and fix one-on-one. But even that will not lessen the level of pain these rouge villians inflict upon our infrastructures.

The above should give great insight why the CIO (Corp. Information Officer) places heavy restrictions on P2P, external USB devices, personal Access Points or Wifi Routers on any client system attached to the infrastructure network -- it's just too easy to inflict massive disruption to everyone.

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J. O. Beard; you + tech-101.com => synergism. Secure your system now