Lead by High Tinker Mekkatorque, the Gnomeregan Exiles are a group of extremely technologically advanced gnomes that make their home in Ironforge's Tinker Town. These gnomes are genius, and therefore quite eccentric.
During the Second War, the gnomes aided the alliance in the war against the Horde by supplying mechanical objects (such as bombs, and flying machines). Their capital city of Gnomeregan was overtaken by troggs. The remaining gnomes fled to Ironforge and Kalimdor's Bael Modan.
Much of this information has been obtained from WowWiki