• by Mark Walsh  @markfwal, March 14, 2011

The iPad 2 is living up to the hype, and surpassing the original Apple tablet when it comes to initial sales. Analysts have estimated the upgraded iPad sold 400,000 to 600,000 units over the weekend, with the device selling out at stores in major cities on Friday only hours after hitting shelves.

Given the iPad sell-outs at Apple Stores as well as  chains like Best Buy and Target, at least one analyst cited by  BGR has estimated opening-weekend sales as high as 1 million units.  

Even the lower estimates, though, put sales of the updated iPad well ahead of the 300,000 the debut model sold in its first weekend last April. The original Apple tablet went on to sell almost 15 million units last year. Besides confirming the iPad still has its mojo and more, another positive sign for Apple is that the majority of buyers over the weekend were new to the device, rather than simply upgrading.

That suggests strong word-of-mouth and publicity about both versions of the iPad are helping Apple broaden its customer base for the device and push it more toward the mainstream. The expansion of retail efforts beyond Apple's owns stores and carrier outlets has certain also played a part in helping the iPad reach a wider audience from day 1.

Surging demand for the new iPad also points to Apple maintaining its dominance of the tablet category this year despite the influx of numerous competitors from Motorola, HTC, Samsung, Research in Motion and others.

At the same time, Apple's rivals are likely to say strong sales of the iPad 2 indirectly benefit them by continuing to expand the market for tablet computers as a whole, as the iPhone did for smartphones. There's something to that. The outbreak of a price war in the category could also help challengers gain a foothold against Apple when it comes to feeding the growing appetite for tablets. But for now, the iPad still defines the emerging tablet niche.

Besides Apple and its carrier and retail partners, strong iPad 2 sales should also come as welcome news to the magazine and newspaper publishers such as Conde Nast, Hearst and News Corps, all of which  have invested heavily in creating digital editions for the device.

With a fresh wave of iPad owners comes a new opportunity to convert new readers to tablet reading and bolster slowing demand for iPad versions of print publications. Publishers can also be more confident in updating their digital editions to take advantage of new capabilities in the iPad 2 -- like twice the processing power, a front-facing camera, and built-in gyroscope.

For advertisers, the new features as well as evidence of a growing iPad audience should also help legitimize the device as a credible advertising vehicle in its own right. And with analysts expected to boost iPad sales estimates to 6 million for this quarter, and a Gleacher & Co. projection of 30 million sold in 2011, that audience is poised to get a lot bigger fast.