Found out tonight, after arguing with one of the local cops, that Baltimore banned mopeds last year. They are classified as "minibikes" and "dirt bikes" (which the city says are the same thing, which is ridiculous). Anything with a saddle (huh?) that is 50 cc or under and cannot be registered with the state is a "dirt bike".
If anyone wants to dig, there was a bill to exempt mopeds and license them (06-0438), but all references to mopeds were struck before the third reading. You can get all that on the city council web page.
I also read through the city ordinances, and the only reference to mopeds is to say they are defined by state law, which doesn't matter, since article 19, section 40 bans them.
I e-mailed my councilcritter, but I guess that if I ride or park anywhere in the city, I'm risking having my moped impounded and auctioned. Since the BPD are cracking down on "dirt bikes" right now, I think I'm screwed.