Indeed, a usable solution today. Still, it's somewhat less convenient than having the radio in the device (eg. an extra device to charge and carry), also potentially more expensive in the short run (depending on the device purchased -- of course). But it indeed works!

For example, I don't own a 3G device. I've considered getting a MiFi (or the Canadian equivalent) and an Archos 70, but the cost ends up being similar to the Galaxy Tab ($550) for lesser hardware and less convenience than an all-in-one pick up and go tablet.

The benefit of this setup is that you can use the MiFi for more than just the tablet device (ie. a laptop) which is quite compelling. Of course, you can do this with a 3G device as well, and even use USB tethering to improve battery life.