Syncing lights to music.

As the title says I am looking to sync lights (BlinkM's) to music.
Is there an easy way to do this on just the arduino? Like a script to match beats. Thanks.

I would go foer shiftbrite LED’s and this:

At 3 Jan 10, the site lists the shield as a very reasonable $18.

hmmm. I like that shield. Thanks..

I forgot to mention that I was going to use Blinkm's to do this.

It probably wont work with BlinkM’s

But Shiftbrites are really cool too, if you haven’t already bought the blinkM’s check the shiftbrites.