The 10 biggest stories of 2011 in mobile tech

This summer, Verizon -- the largest U.S. carrier -- stopped offering unlimited data plans All major U.S. carriers were busy rolling out their faster 4G networks As of October 2011 the Android operating system was used on over 46% of U.S. smartphones Editor's note: Amy Gahran writes about mobile tech for CNN.com. She is a San Francisco Bay Area writer and media consultant whose blog, Contentious.com, explores how people communicate in the online age. (CNN) -- For Americans who own cell phones or other mobile devices (at least 85% of the adult population, according to a new survey), 2011 ushered in a whirlwind of news. Some of the year's top mobile stories were mostly hype (QR codes and cell phone radiation) or vaporware (those persistent iPhone 5 rumors). But other developments were genuinely important to t
he U.S. mobile landscape. Here's a quick -- and entirely subjective -- list of my picks for the 10 most important stories and trends for 2011 in U.S. mobile news: 1. Goodbye (mostly) to unlimited data plans; hello throttling. The digital divide between those with high-speed Internet access and those without remains a huge problem in the United States and elsewhere, leading to significant inequities of opportunities and services. Good mobile devices and networks can help bridge this gap -- if you can afford them. For smartphones, the biggest part of the total cost of ownership is the data plan, which in the United States typically requires a pricey two-year contract with a steep early termination fee. When smartphones first came out, unlimited data plans were the norm. But wireless networks couldn't keep pace with skyrocketing demand for data, so most carriers took down their "all you can eat" signs. This summer Verizon, the largest U.S. carrier, stopped offering unlimited data plans, following AT&T's move from 2010. T-Mobile still offers what it calls "unlimited" data plans, but it caps high-speed data access -- and if you hit your cap, your data speeds may slow to a crawl until the next billing period. As of now, Sprint is the only remaining major U.S. carrier that still offers an unlimited, uncapped, no-throttling data plan for a flat monthly fee. If you happen to live in a city where Sprint's network is fast, that may be a good deal; but according to Rootmetrics, Sprint's data speeds vary widely by location. Also, Sprint is reportedly testing throttling on its Virgin Mobile brand. 2. Growth of mobile streaming media. It seemed to be the year when streaming media for mobile really took off. According to The Nielsen Company, 14% of U.S. mobile users (about 31 million people) now watch videos on their smartphones and feature phones, a 35% increase over last year. Also, 29% of U.S. smartphone users stream music or Internet radio to their phones, up 66% from 2010. This year's U.S. debut of Spotify -- along with new and updated mobile streaming music and video services from Facebook, Amazon, Google, Apple, Netflix, Hulu and video chat/calling services like Google Plus hangouts -- are helping to fuel the demand for streaming mobile media. And behind the scenes, technology from companies like MobiTV are helping streaming video consumers seamlessly shift their viewing experience from one device to another. The catch: Streaming media uses a lot of data bandwidth, which puts a heavy burden on carrier networks. This is probably a key reason why carriers have mostly abandoned unlimited data plans, which brings us to the next big trend, 4G. 3. 4G network rollouts. This year, all major U.S. carriers and several of the discount regional ones were busy rolling out their faster 4G networks. This label comprises three major technologies: long-term evolution (LTE, used by Sprint, Verizon and MetroPCS), HSPA+ (used by AT&T and T-Mobile), and WiMAX (provided by Clearwire and resold by Sprint in some cities). These technologies offer different speeds, strengths and weaknesses -- so what the 4G experience means to consumers will vary widely by carrier and location. Over time, the move to 4G networks should relieve the growing burden on existing 3G carrier networks. They'll also enable new services, such as better and more sophisticated voice calling. But consumers must purchase new 4G-compatible phones to use these networks -- and those will mostly be hitting the U.S. market in 2012. For instance, the new iPhone 4S is only 4G-capable on AT&T's HSPA+ network; Verizon and Sprint users have to settle for 3G speeds, for now. 4. BlackBerry outage and continuing RIM decline. For several years, even after the first iPhone launched, Research in Motion's BlackBerry line of phones was the 800-pound gorilla of the U.S. smartphone market. This was driven mainly by business users, who were attracted to the phone's advanced messaging and encryption features. But BlackBerries also grew popular with U.S. consumers as a lower-end "smart-ish" phone that generally was more affordable than iPhones and higher-end Android phones, and widely available on no-contract plans. Then, on October 10, 2011, RIM experienced its longest and widest outage. Users lost access to their e-mail and BlackBerry Messenger, and some lost Internet access, too. It began in Europe but soon spread elsewhere, eventually affecting the United States. The company had already fallen on hard times, and was struggling to retain its market share and increase its relevance by attempting to update its technology. But as