The first Google phone was finally unveiled at a lavish event in Manhattan, and it's pretty much what we expected: A slim (if not iPhone-slim) QWERTY slider with a generous touchscreen, 3G and Wi-Fi access, GPS, and—most importantly—Android, Google's much-anticipated mobile OS. Do we have an iPhone killer here?

Update: Check out my hands-on impressions of the T-Mobile G1 right here.

I'll be posting a hands-on report a little later, but first, the official details: Expect the T-Mobile G1 to arrive in stores October 22 for $179, about $20 less than we heard last week; a "limited number" of T-Mobile subscribers will be able to pre-order the phone starting today, at T-Mobile's Web site. An unlimited 3G data plan will be available for $25—$5 less than the iPhone 3G's data plan. 

Among the G1's main features: Support for T-Mobile's just-launched 3G network (although, as I wrote last week, only about 21 markets will be covered by the time the G1 arrives in October), Wi-Fi (including seamless roaming between Wi-Fi and 3G, a la the iPhone), GPS, Bluetooth, and a pre-installed 1GB microSD memory card (up to 8GB is supported).

The phone itself? Well, as expected, it's not the smallest handset ever—measuring 4.6 by 2.16 by 0.62 inches and weighing in at about 5.6 ounces, the G1 is somewhat bigger and heavier than the iPhone, although that’s to be expected given the sliding screen, which reveals a full QWERTY keypad beneath. Also, the G1's 3.17-inch display is a bit smaller than the iPhone's 3.5-inch screen.

Of course, the meat of the G1 is its access to Google's online features, and the handset doesn't disappoint: Full-on support for Google Maps (and yes, including Street View), Gmail, YouTube, and Google Talk, along with an HTML browser.

The Street View feature of Google Maps is especially impressive—thanks to the G1's built-in compass, you can get a panoramic, 360-degree view of the scene simply by holding the phone and waving it in any direction. Awesome. (Of course, the typical local business/points of interest search is present and accounted for.)

OK, so how's the touchscreen interface look? I'll have a hands-on report a little later today, but from the demonstration we saw at the press conference, it looks pretty impressive—the closest I've seen to the iPhone yet, complete with on-screen menus, icons, and scrolling lists that looked remarkably smooth and responsive. I'm curious to see if it works as well in person.

As far as messaging goes, the G1 supports push Gmail (natch) as well as POP and IMAP e-mail accounts—no full-on Exchange support, although T-Mobile reps said an Exchange-syncing app would be a "perfect opportunity" for a third-party developer. You can also IM over Google Talk, AOL, Windows Live, and Yahoo Instant Messenger.

Other features: A 3MP camera (upping the ante on the iPhone's 3G's 2MP snapper—although, as with the iPhone, there's no video recording), a music player, and voice recognition.

As far as applications go, a "beta" version of Android Market will come with the G1, along with a handful of applications, including: ShopSavvy, a comparative shopping app; Ecorio, the "green" travel-planning app I blogged about a coupe of weeks ago; and an Amazon MP3 shopping app.

Stay tuned for my hands-on report once T-Mobile lets us take the G1 for a spin. Have any initial questions? Fire away.