And I am a dummy.
Oy. The font was all but unreadable. After digging around I figured out why: apparently the Stone Sans ITC font I used is considered an "obscure" font and thus, converts to something else when it's processed. Something hideous.
Moral: humble yourself and read the FAQ when you're using a new app for the first time. This is explained on the FAQ and also visible when you look at everyone else's uploaded presentations, none of which use "obscure" fonts.
I originally chose the Stone Sans ITC because I took the advice of someone (a famed blogger I'll not name here) who does a ton of presentations who recommended using a more unusual font to make the presentation more memorable. I guess that person doesn't use SlideShare.
So, I'm off to spend an hour or so converting a copy of my slides to boring old Arial Bold for the upload. I'll keep the Stone Sans ITC for the live presentation.
I'll post a link over here once I'm happy with the final product.