Great, BUT.
The problem is many of us own many devices with 3G, soon to be 4G, but we have to pay individually for each device. I really like the idea of MiFi, but it shouldn't come down to that. In addition, I pay MiFi fees and two other account fees as it is, and I am using three devices that don't have 3G on the MiFi too (iPod Touch, MBA, and iPad - I would have bought 3G if I had a universal 3G Internet connection account).
Companies like Verizon and AT&T should sell service to connect all devices for one price. It could even be expensive, or charge tiers, but it has to be less expensive and problematic than opening five accounts.
Apple should include a 3G/4G card in every Mac and iOS device it sells. It doesn't cost $129 for each card as Apple would have us believe. They could do it for probably a few dollars per device, and I am sure wireless carriers would pick up the tab if they had access to sell Internet coverage accounts. Have them in iPod Touches too (every device with OS X or iOS). This could be a huge advantage, and with dual GSM/CDMA cards available, any customer could have all of their Apple products on one Internet account.
My idea on price.
$39.99 unlimited (5GB) for first device.
$4.99 for each additional device to share the data connection plan... (throttle after 5GB or charge $2.99 per each additional GB)
iPhone is first device
iPad is second device
MBA is third device
MBP is fourth device
iPod Touch is fifth device
If I had this setup and all five devices had 3G/4G cards, I would pay $59.99 plus $2.99 for each additional GB over 5GB if I wouldn't accept throttling after 5GB. Right now of course those devices don't all have 3G/4G but they should.
Right now, I pay $40 on MiFi to Virgin Mobile. I pay $30 to Verizon for my iPhone 4 just for its data. I pay $25 for a Virgin Mobile phone that has unlimited 3G Internet, email, texting, and 300 minutes too. It is a pain to carry around my MiFi to use with my iPod Touch, MBA, and iPad, and I would prefer something easier.
I really think it's crazy that no company like Verizon has stepped up and offered this as a convenience and competitive advantage. In addition, one would think that Apple would be on top of making something like this happen so every device it sold could connect to the Internet.
Customers would see value in having Internet on all devices without hassle of separate accounts and separate bills each month, and without paying ridiculous sums if they only use 5GB or less on all devices anyways. Apple would have a huge advantage as its customers would buy the MBA too because the Internet account they have would just work with it. If only Apple was doing it, consider the added sales as people would buy the Mac over PC, iPod Touch over Zune, iPad over Xoom, and iPhone over Android. The power of having the Internet at your fingertips with every device you own, and having one simple bill per month instead of five would be a gigantic competitive advantage.