I occasionally check in at the Wi-Fi Alliance website to see how the dual mode phone certifications are doing. The last time was in February. Today I got an interesting surprise. Massive activity this quarter – over 50 phones. I am very curious to see the results for the fourth quarter – could we have crossed the trough of disillusionment in dual-mode phones?
There are still no 802.11n dual-mode phones – not really surprising considering that only one company claims to be shipping 802.11n mobile phone chips: Redpine Signals; they tell me that their chip is shipping in Wi-Fi only phones, not yet dual-mode. TI’s announced 11n chip will probably ship in phones early next year. 
The fundamental difficulty with 802.11n is power. With the requirement to drive multiple radios, providing 802.11n in a battery-powered device will be a challenge.
The Wi-Fi Alliance has proposed an n-capable interface for voice devices that will use a single transmit chain, and hence, one radio. The advantage of this approach is somewhat in question, because with a single transmit chain, 802.11n doesn’t provide much more capacity than 802.11a or g.
I agre that the outlook looks good for Wi-Fi on the handset, since the growth of smartphones is underway and most fo the top smartphones are now sporting Wi-Fi. [http://imcellular.wordpress.com/2008/11/19/wi-fi-appearing-in-smartphones/] 11 of the top 15 smartphones recently reviewed by PC Magazine include Wi-Fi!
I suspect that there are many motivations, not the least being that operators recognize that the free use of Wi-Fi greatly reduces the burden on their networks, and they foresee an explosion in data use: I’ve seen forecasts of 1000% traffic increase in 5 years). With traffic increasing 1000% and revenues increasing 100%, the operators are in a bind. Hence the desire to offload on Wi-Fi and–even better for Operators–Femtocell. [http://imcellular.wordpress.com/tag/femtocell/]