The family and I were flying SEA>OGG last week. We were all upgraded for the PHL>MSP leg (we were all on one PNR)...6 upgrades to first, with only one Platinum on the PNR (only elite, in fact!). The flight was oversold in the back, so they bumped us all up front to accommodate other passengers.

Anyway, as we were waiting for boarding at SEA, the GA announced that there were upgrades available for purchase for $150. I went up and showed my NW PE card and asked if I could get the upgrade as a PE. Her response....."This is a Delta flight, so we are not offering upgrades to Northwest Elite members". Nice.