The International Consumer Electronics Show kicked off on Tuesday with a dazzling array of high-tech gadgetry including ultra-thin laptops, snazzy smartphones, iPad rivals and flat-screen and 3D TVs.

A record 3,100 companies from around the world have staked out booths in the cavernous Las Vegas Convention Center for the four-day event, displaying their wares over a space equivalent to more than 35 football fields.

The host of CES, the Consumer Electronics Association, forecasts worldwide spending on consumer electronics to surpass $1 trillion this year for the first time with smartphones and tablet computers leading the way.

CEA chief economist Shawn DuBravac said he expects more than 20,000 new products to launch at CES including over 50 new tablet computers as Apple competitors seek to make a mark in a category dominated by the iPad.

Smartphones are also expected to be a hot item with Finland's Nokia teaming up with Microsoft to tackle a US market dominated by the Apple iPhone, Research In Motion's BlackBerry and handsets running Google's Android software.

Microsoft chief executive Steven Ballmer joined Nokia boss Stephen Elop ahead of the show on Monday to unveil the new Lumia 900 smartphone, which will run on Windows mobile software.

Another hot product category on a CES show floor pulsating with music and flashing screens is expected to be the sleek, lightweight laptop computers known as "ultrabooks."

DuBravac said he expects to see between 30 and 50 ultrabooks launched at CES as computer makers again seek to make up ground on Apple and its popular MacBook Air.

Taiwan's Acer on Sunday took the wraps off what it said was the world's thinnest laptop computer, the Acer Aspire 5, which is just 0.59 inches (15 millimeters) at its thickest point and weighs less than three pounds (1.35 kilograms).

Chinese telecom giant Huawei, meanwhile, unveiled what it said was the world's slimmest smartphone, the Android-powered Ascend P1S, which at 0.26 inches (6.68 millimeters), is thinner than a pencil.

The latest in TV technology is also on display as mostly Asian manufacturers show off OLED sets and make another push to bring 3D TV into the home.

Tim Baxter, president of Samsung Electronics America, said half of the TV models sold by the South Korean giant this year will be "3D enabled."

But in a rare admission that 3D TV has not yet caught on in a big way with consumers Baxter said "we know there still isn't enough content to make 3D a 'must have' feature."

While 3D TV may not yet have gone mainstream, more television sets rolling off the manufacturing lines are able to connect to the Internet.

The CEA's DuBravac said 12 percent of the TV sets sold in the United States in 2010 were Internet-enabled but nearly half of all televisions shipping this year will be able to tap into the Web.

Some of them will even be voice-controlled -- welcome news for anyone who has ever struggled with the bewildering array of buttons on a TV remote control.

Cars and home appliances such as refrigerators and dishwashers made smart with sensors, computer chips, and Internet connections will also be among the attention-getters at CES.

Also grabbing attention is Microsoft, which is making its final appearance at CES.

Microsoft chief executive Ballmer or his predecessor, Bill Gates, have delivered the opening keynote address at CES for the past 15 years and the US software giant has traditionally had one of the largest booths on the exhibition floor.

But Microsoft has said this year's show will be its last because the January timing does not coincide with its product development calendar.