There are two interesting things about the Kindle Fire HD.
One is that it introduces parental controls to Android. It even includes OS X like scheduling controls that are missing from iOS 5. I don't know how well they work, but they can't be worse than Apple's feeble restriction system.
The other is the inexpensive $4/month 256MB data plan. That's only enough data for messaging, light email, downloading books (they are tiny!), and perhaps a bit of Facebook on occasion. But it's still a good rate - esp for AT&T. Even Ting, a Sprint MVNO, charges $3/month for only 100MB. The iPad 250MB data plans is $15!
Things are different though as you move to the 3GB mark:
The Catch in Kindle’s Data Plan - Digits - WSJ: "Kindle users who know they’ll want more data will have to pay a lot more than $50 a year: $30 a month for 3 gigabytes or $50 for 5 gigabytes – plus a $36 activation fee (which isn’t charged with the Amazon promotional plan, but will apply to any upgrades)."
Not coincidentally, the iPad is $30 for 3GB on AT&T (LTE).
So it was only at the very low end that Amazon was able to extract a better deal from AT&T. Even so, Amazon got a better deal Apple - that's an achievement even if they're somehow paying AT&T for the honor.
So what's in it for AT&T? They must estimate that a significant number of Fire users will convert to the 30GB plan.
We're all keen to see if Apple gets a similar deal ...