Though uncommon, Macintosh computers can be infected with spyware. Operating Systems - including MacOS and Windows - are complex programs, so they all contain flaws and errors. There is also no shortage of people who would target the growing community of Mac users.
SecureMac.com is a good resource for information on Mac spyware. There are removal tools, scanners and security applications all designed to combat spyware. The administrators of this website have also made a spyware removal tool for older versions of MacOS as well as the current version.
For more information, visit http://www.securemac.com.