From the Online Etymology Dictionary (hi, mav!):
rum (n.)
"liquor from sugar cane or molasses," 1654, originally rumbullion (1651), rombostion (1652), of uncertain origin, perhaps from rum (adj.).
"The chiefe fudling they make in the Island [i.e. Barbados] is Rumbullion alias Kill-Devill, and this is made of suggar cane distilled, a hott, hellish and terrible liquor." [1651]
The Eng. word was borrowed into Du., Ger., Sw., Dan., Sp., Port., It., Fr., and Rus. Used since 1800 in N.Amer. as a general (hostile) name for intoxicating liquors. Rum-runner "smuggler or transporter of illicit liquor" is from 1920.

rum (adj.)
"excellent," 1567, from rome "fine" (1567), said to be from Romany rom "male, husband" (see Romany). A very common 16c. cant word, by 1774 it had come to mean "odd, strange, bad, spurious," perhaps because it had been so often used approvingly by rogues in ref. to one another. This was the main sense after c.1800.
http://www.etymonline.com/index.php?l=r&p=20

Oh my gosh! I wonder if that's how Kill Devil Hills, NC, got its name?? We were told that in the past it was fairly common practice for a plunderer to place a light on the coast so that ship captains would be misled and become shipwrecked. That was certainly a rum business!