kaled - 6:42 pm on Dec 11, 2010 (gmt 0)
A "hack" in programming parlance is a quick and dirty solution to a problem. Therefore, a speed-writing competition in which code is judged for effectiveness (rather than beauty and extensibility, etc.) can therefore be called a "hacking" competition.
That's not to say it's a good choice of name for a competition, but it is reasonably accurate.