Oh, well, probably a good idea

CNet News has more on anti-virus software and the Mac:

Apple is recommending that Mac users install antivirus software. But don't read this as an admission that the Mac operating system is suddenly insecure. It's more a recognition that Mac users are vulnerable to Web application exploits, which have replaced operating system vulnerabilities as the bigger threat to computer users.
On 21 November Apple updated a technical note on its support website that says: "Apple encourages the widespread use of multiple antivirus utilities so that virus programmers have more than one application to circumvent, thus making the whole virus writing process more difficult." The item offers three software suggestions: Intego VirusBarrier X5 and Symantec Norton Anti-Virus 11 for Macintosh, both available from the Apple Online Store, and McAfee VirusScan for Mac.
MacDailyNews unearthed the same note posted by Apple in June of 2007 and published it on Tuesday, along with a link to a March 2002 note from Apple urging people to use an anti-virus program.
Apple representatives did not respond to e-mails seeking comment on Monday, but did return a call on Tuesday. A spokesman said he would look into the matter.

Rico says it surely can't hurt...