Hello,
The original warranties, that is the warranties out of the factory, are valid `WORLDWIDE` for all portable devices, such as iBook, Powerbook and iPod. These serials are open to all Apple service locations WORLDWIDE, and they all see the factory Warranty.
However,
The so called `Extended Warranties` are ONLY VALID locally. When you extend the warranty, ONLY your LOCAL APPLE updates their database, hence the info is not obtainable from other locations. This is the situation for all of the computer companies. (well, most)
Best would be to ring your LOCAL Apple. If they say `YES`, be sure to ask them for a WRITTEN approval, since this is an one-on-one approval, and a future manager/technician can well reject it.
Regards