I read a good article on the myth of warping brake discs a good while back. As Darenspalmer has pointed out, this is often the cause of the so called "warped disc". There are a few other reasons it can happen too.

As for bedding pads in, there are a few tried and tested methods. The quick method is 50-30 gently 5 times then 70-30 starting gently and working up to aggressive, over 5-10 times, seems to work very well for me. either that or drive normally and go fairly easy on them for 100 miles or so. not 100miles straight down the motorway though, that doesnt count.

JAmes.