OSX 10.4.3 was released a few days ago (October 31st). There are quite a large number of fixes in there but an interesting one was “MS-DOS formatted volumes, including the iPod Shuffle, perform better and consistently mount (become available) in the Finder.”
This should fix an issue that Lori’s been finding with her iPod not always showing up in iTunes. Although she syncs it with a mac, it’s been formatted from the Windows iPod updater so that it can be used as a USB hard disk for a PC if she goes somewhere and wants to swap files with friends. Mine was the same but I found that while it always showed up when plugged in, it took significantly longer to show up in Finder than when it was formatted by the mac.
More information about the 10.4.3 update can be found on Apple’s website at http://www.info.apple.com/kbnum/n301984