The Blue cards are on the list of cards that offer contactless (Delta isn't on the list; Starwood is still the only cobranded card on it):

http://www.americanexpress.com/us/co...ntactless.html

I actually came across a photo of a Blue Cash Preferred with EMV and contactless earlier today. Seems like it would work just like any other card; since the card is transparent you can see the antenna wires: http://i.imgur.com/oepLx4y.jpg