如果说微软/诺基亚联盟即将在新兴市场吞噬安卓份额，那么iPhone已经开始在美国这样干了。在威瑞森（Verizon）开始发售iPhone后，安卓在美国智能手机市场的份额已趋于平稳。而随着新款iPhone 4S的上市，安卓的份额正开始下滑。如果苹果能如期在今年秋天发售LTE版iPhone 5，那么可以预见，安卓在美国的份额还将进一步下滑。
人们很容易过度解读市场份额的短期变化。例如，4月份正值欧洲和亚洲经济不景气期，许多功能手机用户都放弃了升级到智能手机的计划，而在总体减速的情况下，安卓手机仍卖得很好。此外，为了对抗苹果的iPhone 5，谷歌似乎已经准备好在今年晚些时候发布安卓5.0 果冻豆（Jelly Bean）。
为iPhone开发应用程序只涉及到一种尺寸的屏幕，而且每次只需考虑一个版本的IOS系统，除非iPhone用户自己懒得升级操作系统。但搭载安卓的设备数不胜数，为其开发和测试应用程序是件极为恼火的事。更祸不单行的是，许多安卓设备升级缓慢，对最新版系统几乎视而不见：只有7%的安卓设备升级到了冰激淋三明治版（Ice Cream Sandwich），即安卓4.0。
For several years, it seemed like nothing could slow the rise of Android. The little mobile operating system that Google bought for $50 million in 2005 was adopted by big smartphone makers like Motorola, HTC and Samsung. Android's share of the global smartphone market rose from about 2% in late 2008 to somewhere between 51% and 59% last quarter (depending on who's counting). Google's foothold in the mobile web seemed assuredly strong.
But it's starting to look like Android's growth may be stalling, just as Google (GOOG) is facing new challenges in mobile from longtime rivals Apple (AAPL) and Facebook (FB). Recent reports suggest the prospect of Android's growth peaking. First, Asymco's Horace Dediu noted that Android's net user gains had slowed for four straight months and that user growth in April was as slow as its been since 2009.
Then another report from IDC said that Android's share of the world smartphone market would decline from 61% this year to 53% in 2016. IDC projected Microsoft's (MSFT) Windows Phone 7 to boost its market share from 5% this year to 19% in four years, thanks largely to the long history in emerging markets of Nokia (NOK), Microsoft's partner in the mobile industry.
And if Microsoft/Nokia will start eating away at Android's share in emerging markets, the iPhone has already been doing that in the U.S. After the iPhone became available on Verizon's (VZ) networks, Android's share of the U.S. smartphone market began to stabilize. And after the release of the iPhone 4S, that market share began to erode. If as expected Apple begins selling a LTE iPhone 5 this fall, Android could see its U.S. share decline further.
It's easy to read too much into short-term changes in market share. In April, for example, economic uncertainty in Europe and Asia led many owners of talk-and-text feature phones to hold off on upgrading to smartphones, and Android phones sold well amid the overall slowdown. And Google seems ready to match an iPhone 5 with Jelly Bean, aka Android 5.0, later this year.
But looking beyond the short-term, there are a few challenges that are likely to cause Google problems in holding onto its formidable presence on the mobile web. First off, the open nature of Andriod -- which allows it to power everything from $99 prepaid phones to high-end Galaxy S3's to Amazon (AMZN) Kindle Fire tablets -- leaves the platform so fragmented it's hard for developers to easily write apps for it.
Writing apps for the iPhone involves a standard size screen and, unless iPhone owners are slow up upgrade their OS, one version of iOS at a time. But writing and testing apps for Android and all its myriad devices can be a daunting task. It doesn't help that many Android devices are slow to upgrade to the latest version of the software: Only 7% of Android devices run Ice Cream Sandwich, a.k.a. Android 4.0.