From The Ticket:

[bigdelta 46]

HALF OFF BUSINESS ELITE UPGRADES. For overseas flyers, there’s some good news this summer for people using miles for upgrades. Until Aug. 31, 2011, Delta is allowing upgrades to Business Elite for 50% fewer miles. For example, transatlantic mileage upgrades are typically 15,000 miles each way. This summer, they can be had for 7,500 miles each way. Upgrades are permitted only on Y, B or M Economy Class fares, which are usually quite expensive, and are subject to availability. Before redeeming miles, it is best to call Delta to see if “Z” availability is open since that is the class that must be open to upgrade with miles (or with systemwide upgrade certificates). No registration is required. Click here for more information. While using miles can be a good deal, keep in mind that Delta often sells Business Elite seats at a discount, which can be even cheaper than a full Economy Class fare, but come with many restrictions. Be sure to research all the options before redeeming your hard-earned miles!