I've been thinking about it a lot and I honestly don't see the logic in people saying that it will have a soldered GPU and will be right around £1500.
The reason being that Apple consider the iMac to be their desktop computer.
What would be the sense in downgrading the spec and price to almost that of the iMac except it could have a couple of pci slots... Really?
Bringing it too close to the iMac and the Mac mini could either canabalise sales from each other, or the MP just wouldn't sell because people would rather have a self contained computer (iMac) or something smaller and still very powerful (mac mini).
My prediction:
1 (maybe even 2) TB fusion drive as standard with still 3 x 3.5" bays free
No optical drive as they want and have the option of the external SuperDrive
Making it smaller cz they gag for that.
Still a graphics card.
Maybe up to four independent monitor slots.
4 pci slots, still optical i/o
8 core base model (who knows what processor)
Siri integration (I don't know if lion has this I'm a snow leopard guy)
And some crazy origami done with the internals so that the air flow is better like the MBP. And some better speakers.
I don't think there will be a "consumer" version, but maybe a semi pro version with less capability. Maybe the base semi pro would be something like 1 thunderbolt, no pci, still 8 core maybe a 4 core option, and still a graphics card. Obviously this would downsize and the price. But if they did this, how would you price it to fit in with every other product without canabilisation?