To the popular press, "hacker" means someone who breaks into computers.
Among programmers it means a good programmer. But the two meanings are
connected. To programmers, "hacker" connotes mastery in the most literal
sense: someone who can make a computer do what he wants-- whether the
computer wants to or not.

To add to the confusion, the noun "hack" also has two senses. It can be
either a compliment or an insult. It's called a hack when you do something
in an ugly way. But when you do something so clever that you somehow beat
the system, that's also called a hack. The word is used more often in the
former than the latter sense, probably because ugly solutions are more
common than brilliant ones.

Believe it or not, the two senses of "hack" are also connected. Ugly and
imaginative solutions have something in common: they both break the rules.
And there is a gradual continuum between rule breaking that's merely ugly
(using duct tape to attach something to your bike) and rule breaking that is
brilliantly imaginative (discarding Euclidean space).

Paul Graham
The Word "Hacker" - http://www.paulgraham.com/gba.html