Google this week announced Android Wear, a version of Android for wearable devices.

The announcement was made in a blog post by Google senior vice president Sundar Pichai, who is responsible for Android, Chrome and Google Apps.

He also announced a downloadable developer preview of Android Wear, as well as a list of partners that includes Asus, HTC, LG, Motorola and Samsung, Broadcom, Imagination, Intel, Mediatek, Qualcomm and Fossil.

The Moto 360 smartwatch. (Photo: Motorola)

It's important to note that from a software developer's perspective, participating in the Android Wear initiative is mostly about Android smartphone app development. To program for an Android Wear smartwatch is to use Google's tools to create an Android smartphone app that talks to the watch.

From the user perspective, the interface is mostly about Google Now -- a voice-based Google service. You say: "OK, Google," then tell your Android watch what you want. Then the watch, using Google Now, will return a screen with the information you requested. Or it will simply take the initiative to show you information, based on Google Now's preemptive search feature or the features built into the smartphone apps that support Android Wear.

So while the focus is on the watch, the key elements are software running on a Bluetooth-connected phone and a cloud service accessed through the phone's Internet connection.

The blog post announcing Android Wear features a video that shows people using either square or circular smartwatches, mostly via a Google Now interface. In the video, users talk to their watches and the watches respond with cards displaying the information requested. The square watches shown in the video look ridiculous -- they're giant, bulky, awkward, clunky devices of the kind that always fail in the market. But the round ones look really good.

It turns out that those are the options for Android Wear when applied to a smartwatch. Developers and smartwatch makers can choose square or round watch faces, and Google's Android Wear SDK will accommodate.

Immediately after Google's announcement, LG announced a square Android Wear smartwatch called the G Watch, and Motorola announced a round one called the Moto 360. The announcement was accompanied by this video.

Motorola is one of the few major companies to release a round-display device of any kind. The round-screen Motorola Aura R1 phone, which shipped in December of 2008, cost $2,000 and flopped in the market. The high price was blamed on the cost of building and supporting the round display.

On the manufacturing side, both LG and Toshiba have developed round screens that could be used by gadget makers, but that was years ago and those screens never really caught on.

Round makes a lot more sense for a wristwatch than it does for a phone. Although it turns out the Moto 360's display within that round watch face isn't quite round (I'll circle back to that point momentarily), the watch looks overall like a winning combination of form, function and features. But the most important facts about the watch -- the ones that will compel you to buy or shun the device -- are still unknown.

What we know about the Moto 360

Of all the smartwatches shipped, announced and rumored, the Moto 360 was the first that made me think: Yes! Yes! This is the smartwatch I want!

For starters, it's just a dumb watch until you want it to be smart. It looks like a physical analog wristwatch. The screen is off by default to preserve the battery. But a motion detector turns the screen on quickly to when you lift your arm to see the time.

The screen is 1.8 in. in diameter, and it flips around so it will read right-side up whether you wear it on the right or left hand.

The Moto 360 is heavily voice- and Google Now-centric like its big brother, the Moto X smartphone. Ask a question and get a result. The watch can also pop up preemptive Google Now notifications and phone notifications, presumably.

The Moto 360 comes with a band that can be swapped with bands made for regular watches, and Motorola itself may offer two or more options, including leather and metal.