During the Google I/O conference this week there was a presentation called
How to NFC. People who were hoping to hear about payments were in for a big disappointment. While the demonstrations were very interesting and innovative not a single one had anything to do with payments.
By the end of the talk they mentioned that card emulation is still not supported in Android and there are good reasons for that. NFC supports a wide range of tag technologies, for instance RFID, FeliCa and MiFare. A single phone can read and write several
tag technologies, but can typically only emulate one. So it's currently a hardware limitation combined with the lack of a single dominating standard for contactless payments.
However, what Android does support is something called peer-to-peer using NDEF Push where data can be sent to another NFC device formatted as an NDEF (NFC Data Exchange Format) message. The speakers strongly recommended this as an alternative to card emulation
for mobile payments, but they were not aware of any such projects yet. It almost sounds like they forgot about their own
project with Citigroup and MasterCard, but more likely that project is using some kind of card emulation anyway to be able to communicate with the VeriFone terminals.