iPhone 3GS: Apple's codename for tomorrow's unveiling?

It's pretty much the eve of Apple's big WWDC press conference, and Daring Fireball's John Gruber is back at the eleventh hour to chime in some more on his previous (and perhaps well-informed) iPhone predictions. He sticks to his previous wagers -- twice the CPU speed, twice the RAM, a heavy emphasis on a new video camera (no word on if there's an additional front-facing one), and $199 / $299 for the 16GB and 32GB models, respectively -- but additionally chimes in that the new device's codename is... drumroll, please... the iPhone 3GS, which he surmises is probably going to be the final product name, as well. Kind of a yawner, if you ask us, but it'd sell like gangbusters no matter what it was called. As for that lowered-tiered iPhone, he's expecting it to be the current 3G model with a price drop to $99. Also on the table is iPhone tethering, which we already know was built into OS 3.0, likely for a fee chosen by each carrier. Teasing farther into the future, he suggests "Marble," codename for an OS X visual overhaul, and the tablet are very much real projects but that there's little to no chance it'll be at WWDC. No clue what the "S" stands for (speed, perhaps?), but at this point we're pretty much counting the minutes to tomorrow's keynote, and our clocks can't tick much faster.