another potential is that before iphone and G1, the us carriers where highly against tethering of any kind for non-business users.

instead they wanted the users to use carrier services.

iirc, some even crippled things like bluetooth by way of custom firmwares to make sure people didnt go outside of said services.

Living in Europe, I can see several factor leading to this:

First here these machines are sold not only in computer stores, but also in cellphones stores eager to expand their lineup. Even if most netbooks don't come with 3G capabilities yet a lot of cellphone stores have expanded into portable consumer electronics such as mp3 players and digital camera, now they added netbooks too and are promoting them heavily.

Second factor is the fact that desktop Linux is somewhat more popular in Europe than in the US, and many Netbooks came with Linux preinstalled, which attracted quite a lot of people not willing to pay for a windows licence.

Third there is the fact that broadband is widely availlable in Europe, often in the form “triple play” packages bundling internet access, digital TV and phone calls. Some people took these offer mainly for the TV and phone services, but given the low price and unobtrusiveness of netbooks are now willing to invest in a 300€ machine just to surf the net and send a few emails.

There are also a few minor factors such as the fact that Europeans are more ready to accept lesser known asian brands (acer for exemple was much better established in Europe than in the US, even before the netbook craze started), the fact that some like MSI released their netbook in Europe before the US etc…

When you consider the pricing vs the shift in how people are using computers it makes a lot of sense.

3G adoption is wider in Europe as well for essentially the same reasons, people use their phones differently than people use their phones here.

Netbooks in the US are going to grow bigtime especially as Verizon and Sprint announce their plans to bundle netbooks and service like Vodafone and O2 are doing in Europe. It'll be interesting to see how everyone approaches this loss leader category.

I'd imagine that with the upcoming “dual-core” netbooks they'll get more expensive but be more powerful, with 6 cell batteries becoming standard and everyone will be able to squeeze enough margin in to turn a profit.

I would add another one to your points:

Supposedly US is quite a bit dependant on car transport, which makes lugging along full size laptop not that much of a problem.

OTOH we, Europeans, rely much more on public transportation, in which case how much the computer you carry weights/how big it is becomes more important.

Though I'm not sure how, in light of my hypothesis, Japan & Korea fits with their, apparently, not very significant numbers… (ok, there's the thing that they're apparently more about advanced cellphones…)

I would add another one to your points:

Supposedly US is quite a bit dependant on car transport, which makes lugging along full size laptop not that much of a problem.

OTOH we, Europeans, rely much more on public transportation, in which case how much the computer you carry weights/how big it is becomes more important.

Though I'm not sure how, in light of my hypothesis, Japan & Korea fits with their, apparently, not very significant numbers… (ok, there's the thing that they're apparently more about advanced cellphones…)