Global wireless USB adapter

I was in Australia last month and met this guy who had a little wireless USB adapter that allowed him to get Internet access anywhere there was a mobile phone signal…I think he paid a flat fee of $50AUD for 1GB…he had gotten it through Optus an Australian tech company but I was wondering is there anything like this which you can buy in the U.S. and take around the world with you? (I will be travelling to Europe, Latin America, and maybe South Africa in the next year.)

I guess you would have to purchase a prepaid plan in each country you were spending time, but it would be great if I didn't have to purchase new hardware each time as well. From what I've researched on the subject so far it seems like you need to get a dual-band adapter, but other than that I'm having a hard time figuring out if what I want to do can even be done realistically.

I have an hp dv3t which I would be taking with me, it's got Bluetooth and draft-n already, running 64-bit Home Edition Windows 7.

Here in the US I use Virgin Mobile Broadband2Go
Broadband2Go - 3G Mobile Broadband Service | Virgin Mobile
I live in the sticks and it's the only option for besides dial-up access. It's $50 a month unlimited data and it actually works quite well. You won't be streaming HD movies with it but youtube stuff plays just fine. The upload speeds are quite low ( I upload a ton of photos to my Picasa account) but I just copy the photos onto a USB stick and do it from my office.
I have no idea if it works outside the U.S. but it is ideal for my home application.