[Suicide Junkie]

Take an overall cloud of particles that may form a planet.
That cloud has some angular momentum. For material orbiting a star, the stuff closer in will be moving faster relative to the stuff farther away. (Since it is orbiting the star)

As the planet forms, the huge starting volume compresses down to a relatively puny ball of rock/ice/gas giant.

Since angular momentum is conserved, and the body is now smaller, the planet will be spinning quite fast.
Think diving or figure skating or merry-go-rounds. When you move the mass towards the center the spin rate increases, conserving angular momentum.
Imagine a merry-go round with a radius of a few million kilometers, collecting 6x10²⁴kg of rock and drawing it down into a ball only 6378 km in radius.

Even a small net spin will be magnified by a huge amount as the body collapses.
Bits spinning too fast may get thrown off, and slow bits will sap energy from the medium and fast bits.

[ August 21, 2003, 16:58: Message edited by: Suicide Junkie ]