You can get at them if you enable the menu item, then select "Mobile Account Preferences" from the dropdown. However, this is as far as I've gotten because I don't have the ability to test to see if this works.

Oh, wow, you're right. (Tip: You have to unlock the Accounts pref pane first to make it show up.) I haven't tried this out, but I almost want to now.

I don't think that's what you think it is. The Home Sync menu I'm familiar with is for mirroring a network home directory on your local disk, in conjunction with another machine running Mac OS X Server. As far as I know, this feature has nothing to do with portable home directories on iPods.