The T-Mobile G-Slate is the U.S. version of the LG Optimus Pad.

It's not just handsets and smartphones at this year's Mobile World Congress' tablets made their way to Barcelona, Spain, as well, despite some people's opinion that tablets aren't really mobile. As an echo to CES this year, Mobile World Congress proved once again that 2011 is the year of the tablet, with the introduction of at least five new models, and the promise of more to come.

The LG Optimus Pad

LG Optimus Pad/T-Mobile G-Slate LG showed up in Barcelona with the LG Optimus Pad, which will be branded in the U.S. as the T-Mobile G-Slate. We already saw a glimpse of it at CES, but this is the first time we got to play around with it.

The display has a 1,280x768-pixel WXGA resolution in wide screen, and a 1GHz dual-core Nvidia Tegra 2 processor is found inside. You also get 1080p HD video decoding, and HDMI support will let you share your 3D video with TVs. Unlike the Optimus 3D, though, you do need glasses to watch 3D video on the tablet.

And as part of the Optimus Pad announcement, LG has a established a partnership with YouTube, which will let Optimus Pad owners quickly upload 3D videos for sharing.

Samsung Galaxy Tab 10.1 Not to be outdone, Samsung also announced a larger version of its Galaxy Tab, dubbed the Galaxy Tab 10.1. It now has a 10.1-inch WXGA display, and it runs the latest Android 3.0 Honeycomb operating system.

Samsung Galaxy Tab 10.1

It, too, will be powered by a dual-core processor (Nvidia's Tegra 2 chipset, naturally), and a few of its features include 1080p HD video recording, an 8-megapixel camera on the back, and a 2-megapixel camera on the front. It'll have both Wi-Fi and HSPA+ support.

HTC Flyer You knew HTC had to get on the tablet bandwagon sooner or later, and it did so in Barcelona with the HTC Flyer. It's supposedly based on Android 2.4, and features a 7-inch super LCD touch screen, with specs that include 1GB RAM, 32GB ROM, 5-megapixel camera on the back, 1.3-megapixel camera on the front, HSPA+ support, Bluetooth, and Wi-Fi. It also encourages pen-based use with built-in sync with apps like Evernote so that you can use it to take notes, draw pictures, and more.

HTC Flyer

ViewPad 4 While its 4-inch size makes it less of a tablet and more of a really big smartphone, ViewSonic also introduced the ViewPad 4, the 4.1-inch cousin to the ViewPad 7 and the ViewPad 10. It'll have a Qualcomm 1GHz processor, a 5-megapixel camera, and a VGA front-facing camera, 2GB ROM, 512MB RAM, Wi-Fi, Bluetooth 2.1, GPS, and a Mini-HDMI output.

RIM plans two more PlayBooks While RIM didn't show off any new PlayBooks, it did at least announce that it plans to have an LTE and HSPA+ version of its tablet later this year.