Moe, Sorry buddy but WiMax is Wireless WAN technology while WIFI is wireless LAN.
The differences are not much, but the cost is Huge. Especially the running cost
WiMax is more suitable for Last mile kind of situations (replacement for Cable or DSL for example) where you want to connect couple of NETWORKS together, the power usage is just too large to be useful for the cheap tried and tested WIFI
You might be interested to know that these WIFI hotspots MAY be connected to each other using WiMax

Moe, you're absolutely right, WiMAX range is staggering up to 50Km, however effectively in our tests we barely had much behind 6Miles (10Km) with a modest throughput of around 2MB/s
Wifi is limited to around 300FT and sometimes with way more expensive AP's it would barely get around 500.
The prices of AP's have dropped considerably, putting the whole 5000 APs in the modest range of 2.5Million dollars, while 1 WiMax tower would be in the range in excess of 400,000$ which can handle .. few hundreds to few thousands depending on the kind
So, with that in mind, the price of Wifi (APs) is totally nothing compared to WiMax.
Now the cost for consumers. A WiFi USB adapter can be obtained for something in the range of $5. Compared to GPRS or EDGE which is +$300. Think if it was WiMax, it would skyrocket the price making it inaccessible to the masses

Now comes the issue of Power consumption. Transmitting 57Mb/s 802.11g 20mw means you have more power for your battery powered device, whereas transmitting to a 50Km away station will require a HUGE amount of power ... WAY MORE than what your cell, PDA or laptop can afford (15 miles need 1W which is 50 times more than wifi which is already horrible on batteries)

Anyway, WiMax is a FANTASTIC technology and using it might be the silver bullet, yet, the standard needs to stabilize, implementations get bake time to take care of the bugs and the price dropped down before it can be rolled out main stream, while WiFI has become way more stable over the past years.

Finally, The concept of wan is like connecting islands of LANs together, especially when there is no Fiber or wired infrastructure available like in 3rd world countries

Again, don't get me wrong, WiMax is fantastic, if you can enable it country wide efficiently, drive the cost down, and implement it as much devices as Wifi then by all means

Only after they discovered it's useless to try and block it... :)

Moe,
If it takes x to transmit a signal 300ft, then it should take x*x*x to send it 600ft, extrapolate to 50km and you will get this

Yes, many companies have promised to proved WiMax devices, but it will reach the price point of WiFi (almost 0 for embedded devices) in the next 4 years (according to Intel, you can double check if you like)

WiFi has just reached the sweet-spot of it's adoption, and WiMax still has a long way to go.

Again, Don't get me wrong, I'm not saying WiMax is bad or that it's not superior to WiFi for long range and what not, but lack of device support, price, power concerns and many other factors WILL delay if not kill the whole effort especially with competing technologies like UWB and what not

Early adopters, will pay a hefty price, and in countries like the US these face a HUGE opposition from the cable companies with their huge infrastructures

The wireless spectrum will see a HUGE amount of growth and change (as has been the case over the past 7 years) with all the alphabet soup they're introducing for every standards, and non-compatible implementations by almost all manufacturers.

SG decided to go with WiFi after careful study, I had no say in it :)

I know, and check your blog, I answered :)

Moey, Hold your pants ....