Computerworld - Apple later today will start selling iPads that are able to connect to the Internet over AT&T's data network. Customers who pre-ordered the more expensive models of the tablet will also receive them today.
Priced from $629 to $829, the 3G-enabled iPad goes on sale at Apple's retail stores and most Best Buy stores at 5 p.m. local time. The company's stores will be closed between 4 p.m. and 5 p.m. to prepare for the sales start.
Today's debut of the 3G iPad follows the April 3 launch of the Wi-Fi-only models. The 3G iPad cost $130 more than the corresponding Wi-Fi-only model, a price increase that at least one expert has called "ridiculous." According to research firm iSuppli, which did a physical teardown of the Wi-Fi model, the additional parts required for 3G connectivity cost an estimated $24.50.
AT&T prepped potential iPad 3G customers earlier this week when it released details (download PDF) about the two data plans that users can access: a $15 per month plan that allows 250MB of data to be transferred to and from the iPad, and a $30 per month unlimited data plan.
Unlike typical cell phone data plans, such as the one that AT&T markets to iPhone owners, the iPad plans are month-to-month deals that can be dropped without penalty. Users who subscribe to the $15 per month plan are warned by the iPad when they have reached the 20%- and 10%-remaining milestones.
Apple also published instructions on its support site today to outline the steps iPad owners take to sign up with an AT&T data plan.
Apple has said it sold more than half a million Wi-Fi-only iPads in the first week of availability, while other estimates -- including Chitika Labs, which calculates sales by tracking unique iPad IP addresses that access its ad network -- are currently as high as 1.17 million units.
The tablet's brisk sales caught Apple by surprise. Earlier this month it said it was adding production to meet the strong demand. Most analysts argued that the shortages forced Apple to delay the international introduction of the iPad to the end of May.
According to Web analytics firm NetApplications, the iPad has captured 0.04% of the worldwide online usage market, meaning that 4 out of every 10,000 devices used to browse the Internet are iPads. The iPad's share of the global online usage market is on par with Research In Motion's BlackBerry and smartphones powered by Google's Android operating system.
Customers who order a WiFi + 3G iPad today at Apple's online store face a week-long wait before their tablets are shipped, according to the company's site.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at 
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. His e-mail address is gkeizer@ix.netcom.com.
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