I don't think backing up the posts to your livejournal backs up your icon stash as well. Since I don't know of a faster way to do this, I went to my icons page and simply clicked on each one and dragged it to a folder on my desktop, so at least I have all of my lj icons in one place, should I need to upload them all somewhere else. PITA, but better than nothing.
If someone has a faster way, comment it here for others to use?
ETA: I've backed up my lj -- how do I upload it to my accounts at GJ, IJ, and JF?