Avaya, Motorola, and Proxim combine on a handset that talks Wi-Fi in an enterprise and cell elsewhere--but only the 802.11a flavor of Wi-Fi: Requiring the use of 802.11a is an interesting choice, because it avoids many of the interference, latency, and dropped packet issues present in using an overtaxed, QoS-free 802.11b/g network. With 802.11a, you could conceivably devote several in-building channels to voice or have a sufficient density and overlap of coverage that you wouldn't suffer from bandwidth lacks.
One analyst quoted in the story suggests that enterprises will eventually all use 802.11a, but I'd like to see some evidence of that. A number of vendors sell a/g equipment for the enterprise, and I've seen no information on an upswing in dual-radio adoption.
A more compelling option for 802.11a is via products that have multiple radios or multiple channels in a single box, such as products powered by Engim's chipset. In that model, because each access point could have several hundred Mbps of actual throughput through bonded or standalone channels, it would be worth deploying the denser installation required by 802.11a. 802.11b and g have substantial limits on total system speed because of their staggered and overlapping channels.