Hey, it's worse than you thought. Many of you have surely already read David Rothman's post on "Library Keyboards and Public Health" -- if not, please go have a look! Time to get paranoid and reactionary about the creepy-crawlers cloying to our keyboards and clinging to our mice. The Krafty Librarian wrote about it too.
The bad news from the article David mentions is: "Potential pathogens cultured from more than 50% of the computers included coagulase-negative staphylococci (100% of keyboards), diphtheroids (80%), Micrococcus species (72%), and Bacillus species (64%). Other pathogens cultured included ORSA (4% of keyboards), OSSA (4%), vancomycin-susceptible Enterococcus species (12%), and nonfermentative gram-negative rods (36%)."
The good news was: "All disinfectants, as well as the sterile water control, were effective at removing or inactivating more than 95% of the test bacteria." So cleaning them works.