Limited unlimited upgrades, you say? I suppose if you'd like to call it that you can, but it is really quite simple. I do understand, it seems you don't, however.

Unlimited- No (quantity) limits. Unlike other airlines, where an allotment of certificates or points is issued, Northwest Elites have the potential to upgrade every Midway flight they fly on a paid fare (on aircraft with a first-class cabin).

Space available- Upgrades are confirmed at check-in (within 2 hours of flight time). Upgrades cannot be confirmed in advance at the usual Northwest Elite upgrade windows.

If you have any other questions, Snake, feel free to slither out from under your rock and ask. While you may not like "unlimited limited" upgrades on Midway, I do! (I even like the "unlimited limited" upgrades on America West for Continental elites) Of course, I would prefer unlimited confirmed upgrades at time of booking on all fares, but (unfortunately) that is not a realistic expectation.