Most Android tablets aren't selling very well and developers aren't quite as keen to develop for them as they were during the tablet hype surrounding the Consumer Electronics Show in January.

Motorola's XOOM tablet has sold only 25,000 to 120,000 units, according Global Equities analyst Trip Chowdhry. Samsung has been at pains to insist that its Galaxy Tab is actually selling well after acknowledging in its January earnings call that the sales figures released earlier in the month, 2 million, reflected units distributed to partners rather than units actually sold.

The Android tablet cause hasn't been helped by Google's decision in March to delay the open-source release of its tablet-tuned version of Android ("Honeycomb") to iron out the bugs. Nor has it been helped by Gartner's prediction in March that Apple's iOS will dominate the media tablet market through 2015.

This is bad news for businesses counting on the commodity pricing that Android promises.

There is a bright spot however: Barnes & Noble's Nook Color, newly refreshed with Android 2.2 ("Froyo"), has sold "millions" of units, according to the company. At $249, the Nook Color is about half the price of Apple's most sparsely appointed iPad 2.

Nevertheless, the stumbling of credible Android-powered challengers to Apple's iPad has affected mobile developers.

Research firm IDC and Appcelerator, maker of a cross-platform mobile development framework, surveyed 2,760 Appcelerator developers in mid-April and found interest in Android tablets isn't growing at the rate seen in January, during the previous installment of what has become a quarterly survey.

In January, interest in developing for Android tablets reached 74%, up 12 percentage points from the Q4, 2010 survey. In April, interest in developing for Android tablets declined three percentage points to 71%.

Scott Schwarzhoff, VP of marketing for Appcelerator, suggested in a phone interview that interest in Android tablet development had stalled.

According to the survey, mobile developers are worried about fragmentation (63%), lackluster Android tablet sales (30%), the growing number of Android stores (28%), and that tablet pricing is too high (27%). Some 22% explained their ambivalence toward Android by saying that iOS is a better mobile operating system, while 19% said they believed they could make more money with Apple. About 13% said they had their hands full with iOS.

Among the respondents, 91% expressed interest in developing for Apple's iPhone and 86% said as much about the company's iPad. These figures are only one percentage point less in each case than they were in January. Interest in developing for Android phones declined two percentage points to 85% since January.

Schwarzhoff said that the margin of error for the study is 2%, which makes it difficult to say anything conclusive about developer interest in iOS or Android phones. iOS is still the platform developers are most focused on and Android the still the platform developers are betting on as the future market leader. This pause in Android's widely assumed world conquest hasn't represented a gain for the less popular mobile platforms. Developer interest in Windows Phone 7 fell to 29%, a decline of seven percentage points since January; developer interest in BlackBerry phones dropped to 27%, a loss of 11 percentage points from interest expressed three months ago.

While Schwarzhoff said that Microsoft's strategic partnership with Nokia has helped make WP7 the third most popular mobile platform, behind iOS and Android, he said he believes Microsoft will face continued difficulty as it tries to catch up. That's what the survey respondents appear to believe as well: Some 60% of them doubt that Microsoft will be able to catch up to Apple or Google. And this may well be a self-fulfilling prophecy because 46% of developers say they're too busy worrying about iOS and Android to devote attention to other platforms.

Mobile development is moving away from monetization through app sales toward revenue generation from multiple streams, including advertising and social tools that promote in-app purchasing, Schwarzhoff said.

Mobile developers also are thinking about apps more as mobile clients for cloud services than as self-contained programs. According to the survey, 84% of respondents expect to connect their apps to public or private cloud services.

Android improvements will come, eventually. Nielsen is reporting that 50% of all smartphones purchased in the U.S. in the last six months were Android phones. The Android tablet picture is bound to improve as well. But while Google and its partners get their acts together, Barnes & Noble's Nook appears to be quietly thriving.

On Monday, Barnes & Noble updated its Nook Color operating system to Android 2.2 and launched its Nook App Store while opening its tablet up to outside developers. The company is selling some 2 million digital book titles, but it is only offering 125 Android apps at the moment. For developers, that represents an opportunity.

To help stock its app store, Barnes & Noble is looking not only to Java-based Android developers, but to mobile developers who prefer third-party frameworks that allow them to write code that can be reused on multiple platforms. The company is supporting Adobe AIR for Android, Ansca Moble's Corona SDK, Mono for Android, PhoneGap, and Unity: Android as alternative development tools.

Carlos Icaza, co-founder and chief evangelist for Ansca Mobile, which has just released a version of its Corona SDK for the Nook Color, said in a phone interview that he has seen a very positive response from the Corona developer community because they appreciate having another venue to monetize their apps. He also cites the Nook's well-defined niche--it's an e-reading tablet--as something that's attractive to developers. Developers appreciate being able to target a specific demographic for e-books and interactive content, he said.

Icaza said he expects the Android tablet market to improve over time, but believes there will be problems while manufacturers fight both among themselves to differentiate their tablets and with Apple for leadership in the market.

"It's getting too crowded in the tablet market," he said. "Everybody has to fight against each other before their can turn their guns on Apple."

The competition at the moment among Android tablet makers, he said, is too much about differentiation through features and not enough about the whole user experience. Over time, he expects that the larger vendors will become more like Apple by seeking to control the whole experience, either through their own operating systems or by adding layers atop Android that enforce their own unique value proposition.