Only Midnight if you are on GMT
The leap-second occurs at a set point in time, ie. midnight UTC. So everybody who doesn't live in the UTC timezone (UK, Ireland, Iceland, Portugal or Morocco) will have the leap-second at some other time, most of you (Europe, Asia, Australia) sometime in early 2009. For me in CADST (that's Central Australian Daylight Savings Time), it's 10:30am on Jan 1, 2009.