I doubt they will be locked
>What can we draw from all this? Orange and T-Mobile will offer heavily
>subsidised but locked 3G iPads in the coming weeks.
There is no need to network lock a handset or other device if you provide it on contract, as the customer has signed a contract of however many months and has in effect committed to pay for it in installments. The handset subsidy is safe because of the contract, not the lock. It is pretty common to get a phone on contract and find it is unlocked, particularly if the carrier is O2 and/or the phone is sold through a third party dealer like Carphone Warehouse of Phones 4 U. Two of my three latest contract phones have come unlocked.
Apple doesn't seem very keen on the idea of locking iPads: I believe that all iPads sold so far have been unlocked, and I doubt Apple will change. Apple seems to be cooling on the idea of locked iPhones for that matter, too, as they have been becoming available unlocked in more and more markets.
I suspect that T-Mobile/Orange will simply be obtaining the same unlocked iPads as everyone else through more or less the same channels as anyone else, and then bundling them with a contract.