I am no expert in military planning, but I would guess we have been moving equipment into the area since September 12th.
I agree with the person that pointed out the real problem is the Scuds, and the type of payload that can be delivered. I am sure we were able to convince Saddam in the first war there would be some serious consequences if biological or chemical weapons were used. But this time around he knows he is a dead man. Regardless of any other goals, his death is close to the top of the list. He has little to lose by using his biological and chemical weapons.
Again, if I had to guess, I would say we are spending time tracking down those Scuds so that they can be taken out in a first strike. I would also guess we are working on some sort of missile defense for our troops and Israel.
I do not believe there will be a big build up, I think it will be a surprise to almost everyone (especially those in the media who have not gotten anything right.
The only thing I am sure of is that Saddam is a dead man walking.
Many military experts have been saying that the "Afghanistan model" can't work against Iraq. Probably so, but numerous, light SOF teams and Kurdish allies will be invaluable in any Scud-hunt in the western desert. The USAF just wasn't quite up to the job last time when it came to detecting-targeting-firing on the Scud launchers. Apparently the Iraqi missiliers were pretty good at getting a shot off before any ordnance could be delivered on their heads. Predator might change this, but I doubt that we have enough of the armed variant to make a significant difference.
Intel says that Iraq probably has only a couple dozen Scuds left. Fine. But what if he arms them with Bio/Chem/Nuke warheads? A few missiles so armed can make a powerful strategic deterrent.