The Earth-shattering Microsoft announcement we've been waiting for is finally here. As several pre-event rumors suggested, Microsoft is indeed building its own tablet.

Make that two tablets. One Windows RT tablet runs an NVIDIA Tegra 3 ARM processor, and the other Windows 8 Pro tablet runs Intel's Ivy Bridge Core i5 chips. One thing that looks really cool are new magnetic covers that are quite reminiscent of Apple's "Smart Cover" for the iPad. But they're a lot smarter—Microsoft's covers actually include a multitouch trackpad and a keyboard. There are two, as we explain in this story: a Touch Cover with virtual keys and a Type Cover with a tactile keyboard and touchpad.

Typing on the cover is twice as efficient as typing on glass, according to Microsoft. There's also a stylus.

10.6-inch devices running Windows 8, the "Surface" tablets borrow their name from Microsoft's table-sized computer that has been an impressive yet niche product for the past few years. (The original Surface has been renamed to PixelSense in a possible attempt to avoid confusion.) In announcing the new tablets, CEO Steve Ballmer stressed that Microsoft has been a hardware company for decades, producing mice, keyboards, webcams, and of course the Xbox, among other products.

While Microsoft typically lets hardware partners build Windows-powered PCs and tablets, Surface hardware is built by Microsoft. "Things work better when hardware and software are considered together," Ballmer said. In what is perhaps a nod toward Apple's so-called "Retina Display" marketing term for high-definition screens, Microsoft said the displays are so good that your eye won't be able to distinguish individual pixels. The exact resolution is unconfirmed, but we do know the tablets feature Gorilla Glass.

"Much like Windows 1.0 needed the mouse, we wanted to give Windows 8 its own companion hardware innovation," Ballmer said.

Here are the specs for the two tablets:

The Intel tablet weighs 903 grams and is 13.5mm thick, while the NVIDIA/Windows RT model weighs 676 grams and is 9.3mm thick. They each have a 10.6-inch display. Office Home & Student 2013 RT is listed for the Windows RT tablet, as well as microSD, USB 2.0, and Micro HD Video. Office isn't listed on the Intel tablet, but x86 Windows 8 devices will run all standard Windows applications. Ports on the Intel tablet include microSDXC, USB 3.0, and Mini DisplayPort.

Even with the cover, the tablets are quite thin, as you can see here:

And here:

The newly unveiled Surface site doesn't say which model is shown in those pictures. In fact, Microsoft's site says these "images are design renderings and not photographs," even though Microsoft did show off actual hardware prototypes at its announcement. In any case, the Windows RT version will be available in 32GB and 64GB flavors, and the Windows 8 Pro device will be available with 64GB or 128GB of storage. Each have front- and rear-facing cameras, and 2x2 MIMO WiFi antennas.

Surface tablets have 16:9 aspect ratio, a built-in kickstand, and edges that are angled at 22 degrees, "a natural position for the PC at rest or in active use," Microsoft says. The casing uses "VaporMg" technology, "a combination of material selection and process to mold metal and deposit particles that creates a finish akin to a luxury watch." These are supposedly the first PCs with a vapor-deposited (PVD) magnesium case, which makes for a device that is thin, light, rigid, and strong.

Microsoft claims it's a tablet that is as great as a PC and a PC that is as great as a tablet. As for availability, the Windows 8 RT tablet will be ready around the time of Windows 8 general availability, a few months from now. The Windows 8 Pro unit will ship a few months after the Windows RT version. They'll be sold in US-based Microsoft retail stores and online. Microsoft said suggested retail pricing will be competitive to a "comparable ARM tablet or Intel Ultrabook-class PC," but we don't know the exact prices yet.

So far, we're not seeing any indication of integrated 3G or 4G cellular connectivity. There are, however, some pretty pictures on the new Microsoft Surface site.

We'll have much more coverage of the new Windows 8 tablets tonight and tomorrow.