The new iPods are for PCs and Macs. However, they come formatted for the Mac.
When yo u install under Windows, part of the setup process reflashes your iPod and formats it as a FAT32 drive.
There is a program out there (search on ipodlounge.com) that enables the PC to read the Mac formatted iPod. That could be a solution for you, but possible only if you are regularly moving between Mac and PC.
It may be that a FAT32 formatted iPod can be mounted on a Mac to look like an external hard drive, in which case you could pull files from it (tunes are renamed and spread across multiple directories), however it is doubtful that iTunes would want to recognise it on the Mac unless it is reformatted as a Mac iPod.
The easiest solution, especially if it is a one off occasion, may well be just to mess around with it on the PC and when you get home start over.