I've not deployed 802.11N yet - much to the constrenation of my customers.  They want the latest and greatest, 802.11N has seemingly been out for years - and we won't support it....I was hoping we'd see new products at CES 2008 that would let us make the leap but it still looks unlikely.

Here are the basics:

802.11B and 802.11G only operate on 2.4Ghz

802.11A operates on 5 Ghz

802.11N can operate on either.

When 802.11N operates on 2.4Ghz, it uses 40mhz - basically the whole spectrum.  The two protocols basically fight.

The solution is to push 802.11N only the 5Ghz and leave 802.11B/G on 2.4Ghz. To do this requires an access point that not only can do both frequencies but both at the same time.  These still don't exist.

I've talked to Linksys - none of their routers can be configured for dual frequency. The new Netgear units don't even appear to have 5Ghz radios.