Sept. 16 (Bloomberg) -- Tablet computers running Google Inc.'s Android will start taking sales from Apple Inc.'s iPad this holiday season and may surpass it in a few years as device makers adopt the software for a slew of models, analysts said.

Samsung Electronics Co. will show the newest Android-based tablet for the U.S. market at an event in New York today, with the country's three largest mobile carriers agreeing to sell the Galaxy Tab, three people familiar with the deal said last week.

Smartphones running Android have already surpassed Apple's iPhone in the U.S., according to researcher Gartner Inc. Google may repeat its success with tablets because its operating system is freely available to any company, said Ed Moran, director of insights at Deloitte Services LP.

"There are a whole slew of factors behind the success: the open-source nature of it, the lower price, it's not proprietary to one company," Moran said in an interview. "Will that port over to the tablet? I don't see why not."

Dell Inc., Acer Inc. and LG Electronics Inc. have said they will make Android tablets. Motorola Inc., which makes Android- based smartphones, hopes to introduce a tablet computer early next year, co-Chief Executive Officer Sanjay Jha said yesterday.

AT&T Inc., Sprint Nextel Corp. and Verizon Wireless intend to announce their support of the Samsung tablet at an event today, the people familiar said, who asked not to be named because the plans weren't public. AT&T and Sprint will subsidize the price, the people said.

The Galaxy tablet, which has a 7-inch screen and can play high-definition videos, will go on sale in Europe in October, according to WP Hong, Samsung's head of global planning.

Though Google doesn't charge for Android, broad adoption of the software may open up related revenue opportunities. The company could increase its mobile advertising sales, expand the market for its search engine and boost its application store, said Jim Friedland, an analyst at Cowen & Co.

"By having an open Android system out there, it's actually accelerating the adoption," Friedland said. "Tablets will increase the amount of time that people stay on some sort of computing device, which expands the traffic and people that Google can monetize."

Android may take three or four years to outsell the iPad as it evolves into a system that can take advantage of the larger screen and video capabilities of tablets, Friedland said. That's similar to the amount of time it took for Android to develop and become popular after the iPhone was released in 2007, he said.

Google, based in Mountain View, California, added 42 cents to $481.06 in Nasdaq Stock Market trading at 4 p.m. New York time. It has lost 22 percent this year. Apple, up 31 percent this year, rose $6.35 to $276.57. Samsung, in Suwon, South Korea, has lost 5.3 percent in Seoul trading this year.

Apple, based in Cupertino, California, sold more than 3 million of the touch-screen iPads, which access the Web and work as a calendar, media player and e-reader, in the first 80 days.

Dell, based in Round Rock, Texas, sells a 5-inch Android tablet called the Streak and will follow up with devices that have larger screens next year.

Android for smartphones surpassed the iPhone and BlackBerry in the U.S. last quarter, Stamford, Connecticut-based Gartner said last month. Globally, Android became the third-most popular operating system, with its market share jumping to 17.2 percent from 1.8 percent a year earlier. Globally, Android trails Nokia Oyj's Symbian and BlackBerry maker Research In Motion Ltd.

The competition for market share is similar to Apple's rivalry with Microsoft Corp. when personal computers began to become popular, Friedland said. Apple had a "cleaner product that was easier to use," though not as many developers worked on the platform because it wasn't as widely deployed. Restrictions on applications that go into the App Store can hold back innovation, he said.

"It's the Wild West," Friedland said. While the programs may be less uniform, "open platforms have historically evolved faster."