The WiMedia Alliance has started certifying radios: The PHY (physical layer) of UWB packages moves forward with certification status. The certification means that multiple chipmakers have been able to provide interoperable silicon at the radio level. Most trade groups won't certify a standard or allow it to move forward until at least three companies have working silicon. In this cases, six firms passed: Alereon, Realtek, Staccato, Tzero, WiQuest, and Wisair.
The next move is the MAC (media access control layer), which is more or less the piece of the puzzle that works with higher-level network protocols (which in turn work with applications) and the PHY for transmitting and decoding information across UWB networks.
After the MAC, certain protocols will then be certified on top of the full radio, with Certified Wireless USB first out of the gate.
At the same time, Alereon announced that they will support higher frequency bands (above 6 GHz) for UWB to allow worldwide customization. This is a big issue, because most the regulatory authorities of most major regions in the world will each have slightly or vastly different requirements and available bands for UWB.