As a followup to my original vertigo post, my sister (who does not have MS) saw a neuro about her vertigo. He seemed to think it was BPPV (benign paroxysmal positioning vertigo--click on Art's link above), and if it got worse for her, she might consider the physical manipulation that Art mentioned. When I saw my neuro, I asked about whether my vertigo episode was due to my MS or not. He didn't seem to think so because it was very short-lived and occurred when I sat up quickly in bed (which is more characteristic of something like BPPV).
For those of you with vertigo that you think may or may not be MS-related, you should read the abstract of the article in the link that Art posted. Sounds like BPPV, not MS activity, was the most common cause of vertigo for the MS patients studied. BPPV can be diagnosed and treated. Without drugs, for a change!