I'm a little sad to see Pluto demoted as a planet. The key question is how we update:
my very educated mother just served us nine pickles
The Economist, always on the forefront of important issues, suggests:
my very educated mother just served us noodles
Kottke had a contest for a planet mnemonics, with this excellent winner (using nine planets as a protest):
My! Very educated morons just screwed up numerous planetariums.