delta airlines upgrade to first class promotion

Fly six qualifying Delta segments anytime between April 1 and June 30, 2011, and you'll receive double flown miles and two upgrades from coach to first class seats. (That's just three nonstop round-trip flights.)
If you qualify for this promotion, you'll enjoy a 75% mileage bonus on all
Delta marketed/operated flights flown July 1 through December 31, 2011.
As a Silver Medallion®, you already earn a 25% mileage bonus. Add that to the 75% mileage bonus and you'll be earning a total bonus of 100%. That's double flown miles on all paid Delta flights.
Also receive two free demestic flight upgrades to first class.
Codeshare flights operated by carriers other than the Delta Connection carriers are excluded from this offer. Additionally, qualified members will also earn two U.S. domestic upgrade eCertificates confirmed at time of booking on any published Economy Class fare. upgrade Certificates is valid for one-way upgrade to first class seats on Delta airlines flights for travel within the 48 contiguous United States and Alaska
The 75% bonus is based on actual miles flown or the 500-mile minimum, whichever is greater. Upgrades earned with this promotion will be fulfilled in the form of an electronic upgrade certificate and will be sent to qualified members by email. Certificate may be used to upgrade on any paid Economy Class fare (that accrues mileage) booked in Y, B, M, H, Q, K, L, U or T class. Upgrades cannot be used on Award Tickets or Pay with Miles tickets.
Upgradeable coach ticket must be purchased according to the applicable fare rules. After booking Economy Class tickets eligible for upgrade, the member whose name appears on the certificate must contact Delta to book the upgrade reservation for the member. Upgrade reservations must be booked in "G" class for First Class and "Z" class for BusinessElite®/Business Class. Seats are subject to limited availability and may not be available on all flights or in all markets. Once confirmed, boarding pass can only be issued on day of departure. Tickets must be validated for travel on Delta. Medallion members traveling in the Economy Class cabin will be permitted two bags free of charge up to 70 lbs. for each bag. All passengers traveling in First/Business Class cabin will still be allowed to check up to three bags up to 70 lbs. at no additional charge on Delta and Delta Connection-operated flights only. Excess, oversize and/or overweight baggage fees may apply.