Visa Mobile on Monday (Dec. 15) threw a major endorsement behind Google's Android mobile OS, pledging that its mobile payments offerings will run on any phone based on Android. As of this week, though, that's a total of one: the T-Mobile G1 phone. A handful of retailers—including 1-800-Flowers, Jos. A. Bank, Planet Hollywood and Overstock.com but excluding any of the top 100 brick-and-mortar chains—went along for the ride, pledging discounts to be beamed to T-Mobile customers using Chase Visa and debit cards. The Visa statement said Chase customers "will have exclusive access to the Visa Mobile application for a limited time." Android is the OS being used by the Open Handset Alliance (OHA), a group that includes Toshiba, Sony Ericsson, Vodafone, Sprint, eBay and Motorola. Although the T-Mobile phone is the only one that today uses Android, others in the group have pledged to ultimately come out with their own versions. The move by Visa, and the retailers such a move brings with it, certainly can't hurt.