You can have cram and jam + engraved iPod
When you order a Powerbook/ibook (or any mac for that matter) on line there are two ways to order an iPod at the the same time - a requirement for the cram and jam promo.
Option1
When configuring your Mac (i.e. adding more memory) you can specify the iPod as an option. At no point are you given the option of engraving the iPod.
Option2
Configure your Mac as required, do not add iPod as an option and once you get to the shopping basket, click continue shopping. Now go to the iPod in the Apple store and click Select, you will now be given an option to engrave the iPod at no cost (free until the offer expires).
Note the above info is for the UK Store, but the US store should be very similar if not identical.
Hope this helps.