From Randy's Milemaster column-

"This is a story about upgrades. In fact, I can just hear Delta SkyMiles calling me now and saying, "I told you so." The Northwest WorldPerks program is just now making this announcement: Effective May 1, 2000, WorldPerks upgrades on domestic Northwest flights will be capacity controlled when upgrading from discounted Coach Class fares. This affects both complimentary Elite upgrades and upgrade awards using your WorldPerks miles. What does this mean? Well, I view it as a sign that the entire frequent flyer program industry is getting their upgrade programs taken to lunch by the increasing demand of upgrade benefits by its members, including the impact that these new alliances are having on elite levels."

See www.biztravel.com for complete story.

I think that this brings Northwest up to par with other airlines. Doesn't every other airline use capacity controls for elite and/or award upgrades?

I think until this announcement Northwest was the only airline not to use capacity controls.

UA has always had capacity controls as far as I can remember. The only other airline without them that I am aware of is AS, only if you are an MVP Gold. Then the booking code is F for your upgraded seat.