Facebook Virus/spyware question

I'll freely admit to being way behind the times when it comes to social networking stuff like facebook and twitter. I had a client ask me if they were virus magnets, and should she stop having her agents use it at work( this was done as I was repairing an infected computer). Now, I have heard that people are doing marketing and sales via facebook, so I don't want to eliminate a potential tool for her agents, but I don't want infected computers either.

So question - is facebook a serious malware threat? Web articles to read would be most appreciated.

Thanks all
Rob

Facebook, according to TRUSTe, is in the top 10 most trust worthy sites.

http://www.truste.com/about_TRUSTe/press-room/news_truste_2009_most_trusted_companies_for_privacy.html

The only potential problem with viruses come in the form of Hoax'. The latest one is where rumors were spreading that a particular app was actually a virus. What the unsuspecting person would do upon hearing that is, google "facebook app virus" and then land on malicious sites. The site would then have them download/install a virus removal tool (actual virus) and pretend to clean their system, of the made up infection.

http://mashable.com/2009/09/14/fan-check-application-virus/

Titan - thanks! Appreciate the information.