Isis were planning to have the first deployments ready and start accepting transactions at the end of summer. Austin and Salt Lake City was selected as the first cities where the solution would be trialed. But unfortunately, some snags lead to delays. (Read here). Good news was that the delay was not too long with the promised launch taking place this month - a bit late for summer (but just) (Read here).
The reason why this offering is interesting (and probably on the right track) is that the security is based on a special SIM card. (In other words, the secure element resides on the SIM). It also seems that the participating operators have constructed a commercial model that could potentially work. This is much more likely to succeed than Google wallet.