I think we are all missing one point here.
Most of us wish the new model will be the same footprint as the

TV/Time Capsule, allowing for a 3.5" drive, real (decent) GPU with dedicated RAM, perhaps even built-in power supply. With a maximum of 4GB RAM, superdrive and 802.11n standard even in the low-end model of course.
I think that covers most of it.
However, rumors point the other way. An even
smaller Mac mini! Why?
When the Mac mini was introduced, most of us were wondering: why make it so small? It costs more because of its 2.5" drive, it's slower because of it! Nobody needs a computer to be that small, the usual PC tower is about 10 times bigger, if not more! Why put a slot-drive in there, a tray-load drive costs about 25$! Etc, etc...
But look at all the marketing it generated. However, other companies have catched up with the Mac mini (Aopen miniPC being the only example I can think of right now).
What's so wrong about an even smaller desktop if the performance is still there? Yes, mechanical 1.8" drives are even slower, however I bet Apple pays less for a 160GB in 1.8" than 160GB in 2.5", because of their much higher buying volume for the iPod classic. That takes care of the "smaller drive = more expensive" problem.
And as flash prices continue to go down, the computer will switch to that, making the whole "smaller physical size = slower drive" problem a thing of the past too.
And since Apple is always designing for the future (remember the death of the floppy?), I can easily see the new Mac mini without an optical drive, letting buyers purchase the MacBook Air external superdrive.
Anyway, if this Mac is supposed to be for switchers, then you should already have a CD/DVD drive in your Windows PC right? It also allows Apple to make the computer even smaller.
If you do buy the external drive, it just sits on top of the Mac mini (just like my Mac mini is sitting on top of two miniStack 3.5" external drives), which takes no more desk space than the computer alone.
Mac nano? Mac Air? Who knows.
I say we only have 4 days to go. Next tuesday also happens to be Apple's 32th anniversary. I think we're all in for a surprise!