in windows it is. Explorer can browse an FTP site almost exactly as it can browse a disk drive. And there are programs like webdrive that allow you to actually mount an FTP server AS a disk drive (there's a free one from IBM or Novell that doesn't has as many options but may work just as well in this case).
And on a Mac you can (I'm assuming) use Fuse or CurlFTPFS to mount an FTP as a drive (they're both linux apps, one probably works for a mac)
And barely better than nothing? What, are you planning on formatting your iPod from windows? The desire for disk access on an iPod = the desire to use it as a flash drive. FTP gives you this just as well as anything else, the ONLY restriction (given it's a somewhat annoying one) is that you need wireless to use it. If that's not a problem (it's not for me), then FTP is the same as "real" disk access.