Yes it does void the warrant. In my case the warranty had expired and I was looking at a doorstop if I did not do something. as I said if you do not know what you are doing it can be a bit tricky:

Instructions can be found here:

Battery Replacement

It is not brain surgery, and it saved me $65 hence I thought I would share it.

In the video they offer replacement for $29.95 I recon it is with shipping, which would run me close to the amount above from Canaduh...