Ran across this on the This Old House site:
Despite the jokes that so often seem to accompany media reports of nail-gun accidents, the rising frequency of such injuries is nothing to laugh at: There are some 14,800 incidents a year among nonprofessionals, according to reports. Most injuries are simple, treatable puncture wounds. But gun-driven nails can also cause more serious problems. They’re powerful enough to fracture bones, including the ones that surround your very delicate gray matter. To keep yourself safe, read your tool manual.