Although the Kindle was earning Sprint only $2 ARPU, the carrier was still reaping huge profit margins as Amazon picked up most of the operational costs.

But they say one in two marriages end in divorce, right? This couple is no exception. Amazon Kindle Director Russell Baker confirmed Amazon is dumping Sprint for AT&T so that it can support international users, according to FierceWireless.

“Sprint’s network uses CDMA technology, while AT&T’s uses the much more widespread GSM technology … Amazon’s decision to drop the CDMA Kindle is a blow to Sprint, which in the first quarter of the year touted its sales of the Amazon Kindle e-reader device as driving the majority of its 394,000 wholesale additions.”

No word from Sprint yet on this. We hope they’re not drowning their sorrows in a gallon of Edy’s, as we’re prone to do after a bad breakup.

UPDATE: Sprint spokeswoman Stephanie Greenwood responds.

The Kindle DX operates on the Sprint mobile broadband network, so Kindles currently in use or already in the sales pipeline will still be powered by Sprint. Sprint has enjoyed a long and successful relationship with Amazon—since the Kindle first launched. We understand their international strategy and look forward to working with them on future projects.

In the old days, AT&T probably would have developed the inner-workings itself. But this partnership is about speed to market, and Jasper Wireless’s whole reason for existence is to “provide the platform, applications and design services needed to profitably connect and manage devices worldwide.”

By using the billing capabilities in Jasper’s software and AT&T’s wireless network, AT&T hopes to create a billing “relationship” with customers more quickly. In this multi-year agreement, Jasper brings its service platform to the table with the applications that help customers build, deploy and manage connected devices. AT&T is Jasper’s exclusive U.S. carrier for its wireless platform.

In a recent New York Times interview, Glenn Lurie, president, Emerging Devices and Resale, AT&T Mobility and Consumer Markets, acknowledged that while there’s a flurry of market activity around wireless access for gadgets, the market is in its infancy. I was relieved that Lurie sounded very clear that no one is clear what the business model looks like yet. Specifically he said: “You’re going to see a lot of people throw a lot of things out there and see what sticks.”

Maybe it will be a little bit like Apple’s iPhone apps. It seems every time I turn on the TV, I’m told that no matter what I might need, Apple’s iPhone has an app for that. Maybe wireless operators will want me to have all sorts of convenient wireless services.

Think Amazon Kindle. The AT&T partnership was announced the day after Amazon said it would release yet another Kindle in June. The Kindle DX is a large-screen (9.7 inch) version optimized for newspapers and magazines for $498. Now I am a recent Kindle 2 owner, and every time I download a book to my device in a matter of seconds, I think about the Amazon model of offering customers “free” wireless access. Since the Kindle’s launch in 2007, Amazon’s whisper-quiet partner has been Sprint, which runs the Whispernet (EVDO) network. Wispernet delivers e-books to me quickly and quietly. Someone pays for it of course, but for once, it’s not me.

The Amazon Kindle/Sprint Whispernet deal no doubt gets other operators’ attention. Sprint may provide the access, and other operators may want to go farther and get a more direct cut of the content. AT&T’s Lurie believes Jasper Wireless can help AT&T get into the wireless device market faster.

According to AT&T:

For some AT&T powered devices, Jasper Wireless’s applications will provide automated operational management capabilities, including custom device provisioning, instant activation, real-time diagnostic tools and detailed billing and usage reports – managed through a Jasper Wireless core software-as-a-service platform designed exclusively for M2M and consumer electronics communications.

By all means, companies should experiment, and wireless operators need to find a comfortable revenue stream, maybe even one that doesn’t make them mere transport providers. Lurie says AT&T wants to experiment with different models that could include charging customers for short-term or prepaid wireless access – both of which sound interesting.

Being a service-provider supporter, somewhere in all of the experimentation, I hope something lucrative sticks.