Apple on Wednesday took the wraps off its long-rumored tablet device, with CEO Steve Jobs showcasing the iPad during a product event in San Francisco. Slated to arrive at the end of March, the iPad will start at $499 for a Wi-Fi-equipped 16GB model. Apple will also sell 32GB and 64GB versions of the iPad for $599 and $699, respectively.

You’ll be able to add 3G connectivity to each of them for $130 more, with the 3G models arriving roughly a month after the iPad arrives in stores.

A slate that looks much like a larger iPhone, the iPad features a home button, a MacBook-like aluminum bezel and a glass screen. It’s a half-inch thick, weighs 1.5 pounds, and has a 9.7-inch LCD screen (with 1024 by 768 resolution). It will use a custom-made 1GHz CPU and flash storage and, Jobs claimed, will get up to 10 straight hours of battery life or a month of life on standby.

The iPad runs on a 1GHz Apple A4 chip. That’s an Apple-built processor resulting from the company’s April 2008 purchase of PA Semi, which specialized in low-power processors.

For connectivity, in addition to the optional 3G, it has 802.11n, Wi-Fi, and Bluetooth 2.1; it syncs to a Mac via USB. To feed those 3G connections, Jobs also announced two new cellular data plans from AT&T: $14.99 a month for 250MB of data, $29.99 a month for unlimited data; both are prepaid, meaning neither requires a contract like the two-year commitment that iPhone users must make.

Here are four biggest/best revelations from Apple's big event.

The prices: Leading up to today's event, pricing rumors were all over the map, but most touted estimates in the range of $700 to $1000. So it was quite a shocker to learn that the iPad would start at just $499 for a 16GB Wi-Fi model. Let's put that in perspective: it's the same price as a 32GB iPod touch just two years ago, and only $200 more than the current 32GB touch, despite having a much larger screen, more powerful hardware, and more features. But perhaps the more telling comparison is that Amazon's similarly-size Kindle DX, with its non-color, non-touch-sensitive screen and much more limited functionality, is priced at $489. Unless you're a hardcore e-ink fan, the iPad seems like a relative bargain in comparison.

Pre-paid, no-contract, unlocked 3G: There were plenty of rumors about 3G wireless support, but the big surprise was the iPad's options for getting 3G service. Unlike the iPhone, where you're locked into a two-year contract at $30 a month, AT&T will offer two iPad data plans: $15 a month for 250MB of data, or $30 a month for unlimited data. The kicker? These are pre-paid, no-contract rates, and you can activate service at any time right from the iPad itself. So you can, say, enable 3G service before a big trip and cancel service when you get back.

Of course, these plans get you 3G service with AT&T--the mention of which drew audible groans from those in attendance at Apple's event. But the other part of the 3G surprise was that 3G iPad models will ship unlocked. Which means you should be able to plop in a SIM card for another GSM 3G network provider and avoid AT&T altogether, as well as use your US iPad overseas by buying a prepaid SIM card. (Update: It's actually a Micro SIM card, which not all providers currently offer.)

iWork for iPad: If the iPad really was just a big iPod touch, certain segments of the tech-buying public--business users and education, especially--may not have seriously considered purchasing it. But with the announcement of iWork for iPad, the iPad became a device that will also let you create, edit, and present Keynote presentations; work on spreadsheets and word-processing documents; and create newsletters and other basic page-layout documents. And support for Microsoft Office documents means you can import and work with Word, Excel, and PowerPoint files. It remains to be seen how well iWork for iPad handles these types of files, and what features it does and doesn't support, but with a real "office suite," a 9.7-inch screen, and the aforementioned support for external keyboards, the iPad is a much more capable tool than it's smaller sibling--and for many people, possibly a laptop replacement.

ePub support: Most people expected the iPad to double as an e-book reader. But Apple's announcement that the iPad's iBooks e-reading app will support the ePub standard was big news. Adopted by the International Digital Publishing Forum (IDPF) as an open-standards-based format for digital books, ePub allows publishers to create books in a single format for distribution to various e-book resellers and for use on any device that supports ePub. With more and more publishers and hardware vendors adopting the ePub standard, this news means it will be easier for publishers--big and small--to make their e-books available for the iPad and other e-readers.