The term has become popular in the computer world, where the security of computer systems is often tested by tiger teams; one of the earliest examples was with the Multics operating system. A subset of tiger teams are professional crackers, testing the security of military computer installations by attempting remote attacks via networks or supposedly "secure" communication channels. Some of their escapades, if declassified, would probably rank among the greatest hacks of all times.
Recently, and more generally, it has some to mean any official inspection team or special "firefighting" group called in to look at a problem.
This article was originally based on material from FOLDOC, used with permission.