As far as I know, none of the standard ebook ereaders currently supports synching via USB. Stanza, does support wifi sharing. You might have to open a port on your router (depending on how it is locked down), but once it is configured, just enable sharing with the desktop version of Stanza, and then you can share books fairly easily between the iPod version of Stanza and the Desktop version.
Alas, eReader, essentially requires downloading the book via a web server; you can upload to ereader, then download, or you can place your books on a web site somewhere (like your home machine) and then download. Its a little clunky. On the plus side though, any ereader books you already purchased from fictionwise can be downloaded again for free.