Google's trials of NFC-based phone payments gained more tangible details through a leak early Monday. The plan described by the WSJ would allow Citigroup debit and MasterCard credit card owners to make payments by swiping a Nexus S, or future Android 2.3 phones with NFC, near a reader at the counter. VeriFone would still be involved, the sources said, and would be the one providing the payment machines.