Yeah, its one of those words that sound the same things.. Interesting, bear with me, I'll be a geek and look up the etymology.
EDIT - here it is
jail c.1275,
gayhol, from O.N.Fr.
gaiole and O.Fr.
jaole, both meaning "a cage, prison," from M.L.
gabiola, from L.L.
caveola, dim. of L.
cavea "cage." Both forms carried into M.E.; now pronounced "jail" however it is spelled. Norman-derived
gaol (preferred in Britain) is "chiefly due to statutory and official tradition" [OED]. The verb "to put in jail" is from 1604.
Jailbird is 1603, an allusion to a caged bird.
Jail-break "prison escape" is from 1910.
Jail bait "girl under the legal age of consent" is attested from 1934.
gaol see
jail, you tea-sodden football hooligan.