Google is developing its own NFC-based wireless payment system that could go head-to-head with not just possible options from Apple but also upcoming industry standards, a pair of insiders said Tuesday. The approach would let users buy goods at stores with an Android 2.3 or later phone like the Nexus S just by getting close to an NFC transceiver. As expected, it would involve an ad system, Bloomberg said, and could arrive later in 2011.