Alternate-History Technologies in Planescape?

Ancient Greek and Roman technology was just plain awesome. Fact is, it surpassed medieval civilizations by far. They had running water, aqueducts, superior knowledge in many scientific areas and for some time even a form of democracy. If you want to use steam-based technology feel you might feel free to do so. For example, Archimedes of Syracuse designed a steam-based cannon that actually would have worked (unfortunately Roman soldiers killed him during the raid of the city).

Oh, sure. Spelljamming space-pirates never could sell their firearms on the planes, because a flintlock is nice against a crowd of sailors flying past you upside-down at 50 feet, but it's cheaper and safer to deal with a barbazu across the pub with a crossbow. I could see firearm use being common among officers on Acheron, though. Same sort of situation.

Actually, Ravenloft already has a good deal of more "advanced" technology and since most everything in Ravenloft comes from somewhere else, that technology must exist somewhere else on the planes. I imagine it would be a nice addition of tone to a campaign if this technology now finally spreads out from, say, the Prime or Mechanus to the other planes. People will try to find out how to make use of it (dripping holy water on bullets to screw some fiends) or reject it (what do I need this for when I have my magic missiles?), enhance it (gnome steam tank) or twist it (Baatezu steam tank) and they will most certainly trade with it.

I'd take this one step further and say that the grotesque mixture only goes to further prove how much of Sigil is based off of Victorian England (specifically, London). I remember reading somewhere (no clue where) that one of the original authors of Planescape had a copy of Victorian Underworld on hand; I've read it myself and highly recommend it to anyone. A lot of the flavor in the book is directly transferable into Planescape as-is, and it's great for explaining the tribalism of the "Hive" and the mindset of its ever-so-cunning criminal elements--as well as the technology they employed.

I too think that steam technology and associated aesthetics blends well with the Victorian trappings of the Planescape Campaign Setting, and most of all with Sigil. One can expect more fantastic vistas in planes such as Elysium or Arborea. In either case, how would steam technology change the logistics and tactics of the Blood War? Would fiends enter the battlefield on locomotives or fight with steam tanks? Would keepers of knowledge across the planes store their information in analog computers such as difference engines?