Threadwatch reports that Business.com has added the nofollow attribute, a method of telling search engines not to count particular links as a "vote," to many of its outbound links. Aaron Wall discusses how the use of the nofollow in this sense "muddies their credibility" by saying they have links in their directory that they don't trust. But it appears that only those that pay Business.com for a directory listing get a link without the nofollow added to it. Everyone else who is accepted into the directory, is tagged as untrusted. That's the exact opposite of how Google's Matt Cutts has said he thinks nofollow should work.
Postscript: Business.com - Use of "No Follow" Tags Explained has Business.com explaining why it uses nofollow in some cases and not in others.
Postscript 2: Business.com's "No Follow" Policy Revision has Business.com changing how it uses nofollow.