I don't know if you have tried this (I have), but if you attempt to sync your iPhone with any computer other than the one you originally synced with your iPhone, you will receive a warning that your iPhone is "synced with another iTunes library." Your only choice at this point is to "Cancel" the operation or "Erase and Sync" because your iPhone can only be synced to one iTunes library at a time. Or CAN it?
Thanks to a set of most excellent instructions from the Shiny Things blog of Andrew Grant located here, you can sync your iPhone with one or more additional computers. Read on to learn more!
As I said before, Andrew Grant has posted excellent instructions to sync your iPhone with computers other than your original. Rather than go into repeating all the details of this method, I will instead provide an overview of the steps that Andrew has put together and refer you to his blog for the detailed, play-by-play so you can do this yourself!
In order to sync to more than one computer, there are some needed modifications to iTunes that will then let you sync different data on your iPhone with more than one computer. For example, you may want to sync contacts and calendar items on your work machine, but sync all your media (songs, podcasts, movies, etc.) on your home computer.
According to Andrew Grant (thanks for your hard work on this, Andrew!), the first thing you want to do is backup "iTunes Music Library.xml" and "iTunes Music Library" (Tunes Music Library.itl on a PC) to a safe location on the computer you want to sync with. You will modify these files so you can safely sync with this computer.
On the computer you currently sync your iPhone with, find your iTunes Library ID. Andrew has posted instructions on how this is done. The idea here is that you want your second machine to have the same iTunes Library ID that the original has so your iPhone won't know the difference. Again, this process is explained in detail by Andrew.
Once you have followed all of Andrew's instructions, you should be able to plug your iPhone into the second machine, select "Manually manage music and videos", you will NOT be prompted to erase any data, and you are ready to roll! Again, special thanks to Andrew Grant for posting this handy tip on his blog. Make sure you go to his blog and follow the steps precisely.
Disclaimer: Tip o’ the Week makes no guarantee, express or implied, that any tip found herein will be new or particularly useful to the reader (and please remember that any time you are being sneaky with your iPhone and syncing, you do so at your OWN risk!)