Several new gadgets have been announced and planned for release this year, but the one category of device that has caused the most buzz has been the tablet.

Tablet computers have been around since before the iPad, but they did not really catch on. When Apple launched the iPad on April 3, 2010, units sold well. Everybody wanted an iPad, and Apple had little to no competition in the tablet market.

Fast forward to quarter four of 2010, where Samsung released an iPad competitor known as the Samsung Galaxy S Tablet. It ran Android 2.2 (Froyo) for its operating system, had dual cameras for video chat, and, like the iPad, it also had a one-gigahertz processor.

Samsung released the Galaxy S Tablet to all four major cellular companies in the United States, and it sold moderately well. Now, a Wifi-only version is set to be released in the first quarter of this year.

Even though iPad clones running old and obsolete versions of the Android operating system appeared on the market right after the iPad launched, the Galaxy S Tablet was the first real iPad tablet competitor (assuming most people considered the Dell Streak a large phone instead of a tablet).

So far this year, however, the message from other tablet producing companies has been something akin to, “Apple is going down.”

Fans have duly noted Apple’s lack of announcements regarding the iPad 2. This has left the stage open for other competitors though, namely Android tablets.

One tablet that caused quite a stir when it was first announced was the Adam tablet, running Android OS 2.3 (Gingerbread). It’s made by a company out of India known as Notion Ink.

The tablet has already been shipped to a select group of customers who were quick enough to pre-order it in December 2010.

Another pre-order wave has not yet been announced, and it is uncertain when the general public will be able to purchase the device.

What makes the Adam Tablet truly special is its interface software known as “Eden.” The tablet will support removable storage devices that are plugged into it (it has USB ports and an SD Card port), and it can even charge other USB devices that are plugged into it.

Upon initial launch, the Adam Tablet will not have access to Google’s Market where people download apps. Instead, it will ship with a special market for apps made by Notion Ink themselves. However, Notion Ink promised that a future update will enable the tablet access to the Google Marketplace in the future.

Motorola’s new Android tablet (now rumored to be launching February 17 according to Engadget.com) won the “Best in Show” award at CES.

The tablet will run Android 3.0 (Honeycomb), a special version of the Android OS that Google designed just for tablet computers.

Their new tablet is called the Xoom, and it features a dual core processor, Android OS 3.0 and 4G compatibility with Verizon’s new LTE 4G network.

Dell has announced and showed off a larger version of its mini tablet, the Streak. The new Streak will come with a seven-inch screen and will be shipped with Android 2.2 (Froyo), but is compatible with over-the-air upgrades for Android 2.3 and 3.0 when they become available.

Android may have had several major victories in the first couple months of 2011, but it is not the only tablet operating system that seeks to be the “iPad killer.”

Research In Motion Ltd., the maker of the popular Blackberry phones, has also announced and exhibited a new tablet known as the Playbook.

It will run a custom operating system made by RIM, and Jim Balsillie, Co-Chief Executive Officer of RIM, said the Playbook is three times faster than the iPad.

“Go to YouTube and see it, it’s fast,” Balsillie said.

Windows also plans to take a shot at Apple’s iPad this year. Companies like Asus and Lenovo showed their Windows tablets at CES, but they didn’t garner near as much attention as any of the other tablets there. That isn’t to say they won’t do well in the tablet war this year, but so far they’ve yet to generate any real buzz with gadget fans.

Apple has been tight-lipped about the rumored “iPad 2” that is supposed to be announced sometime within the next couple months.

Rumors are swirling that new iPad will have a better display and dual cameras for Apple’s video chat program “Facetime.”

As 2011 continues, the tablet war will only heat up as more tablets are announced and released.