Wi-Fi evolutions tend to lag in embeded devices, because of the difficulty of integrating a Wi-Fi stack into a small device with low battery- and brain-power, and a specialised embedded OS.
Wi-Fi phones, for instance, are now mostly on the 802.11g standard (though do check, as there are still 802.11b devices out there) - but they were stuck on the older 802.11b for a long while after 802.11g became the de facto standard in all other Wi-Fi kit.
And phones have standard operating systems and large markets, as well as comparatively big batteries and processors. In other embedded applications, such as remote monitoring devices, Wi-Fi is still a rarity.
As 802.11n emerges, the same lag will happen - although the situation will be complicated because 802.11n devices will need multiple antennas, and it's not yet clear how easily these can be built into a small device where they may not have much separation.
Ezurio (formerly TDK) wants to speed things up for 802.11n, so it's come out with embedded 802.11n modules the size of a postage stamp, using a Green Hills embedded OS.
As well as the arrival of 802.11n, there's another factor that makes this a good time to embed Wi-Fi. Machine to machine applications are growing, and these require small modules that have intelligence and networking to communicate to each other.