With its next blockbuster smartphone—the iPhone 4—primed for another hypetastic launch on Thursday, Apple is continuing to tout the huge success of another product: the iPad. According to Apple, the company has now sold 3 million iPad tablets, which is indeed an impressive milestone. But why does the company generate a PR announcement each time it sells another million iPads—something it doesn't do for other products? And why is it undercutting the amount of time it has taken to sell this many units?

Apple's iPad became available for sale on March 12. So, assuming that Apple announces each millionth milestone the day it actually happens, it took the company 102 days, or about 14.5 weeks, to generate 3 million in unit sales. Impressive? Absolutely. Apple is selling more than 200,000 iPads each week and is on track to sell about 8.5 million units by the end of 2010.

But Apple doesn't measure iPad sales from that date. Rather, it measures sales back to April 3, knocking off about 3 weeks of time and making the statistic seem a bit more impressive. Apple claims to have sold 3 million iPads in just 80 days, even though it's taken over 100 days.

Yes, the iPad was first physically delivered to customers on April 3; that was the first day that a customer could walk into an Apple Store and pick one up. But the actual sales period dates back to March 12, not April 3. What Apple is really commemorating is units delivered to customers, not sales. And since the iPad is in a constant state of being nearly sold out, the difference is actually important: Apple couldn't have actually sold more iPads in this time period because it is, in its own words, "making them as fast as they can." So, those 80 days of sales actually include several additional weeks of ramping up to get inventory to market—weeks during which the company was in fact taking sales and gauging demand. It made sales before the April 3 date. Lots of sales.

Why is Apple so desperate to make the iPad—already a phenomenally successful product by any definition—appear even more successful than it is? Clearly, the company and its CEO have a lot riding on this product, and with Apple promoting the iPad as a new device category, its credibility and standing as an industry innovator are at stake. The iPad can't just be successful. It must be undeniably successful, a fitting legacy for CEO Steve Jobs, whom many feel could retire suddenly and at any moment.

Here's the thing: Neither Apple nor Jobs needs to (ahem) pad the iPad's stats or influence. As with Apple's other iconic products, including the iPod and iPhone, competitors are scrambling to come up with suitable alternatives to the iPad, and as before, they're doing so in a time-wasting, fumbling way that will ensure that Apple has yet another market completely to itself for months if not years.

Compared with best-selling consumer electronics products such as MP3 players, cell phones, smartphones, DVD players, or PCs, the iPad isn't exactly setting the world on fire. But since this is indeed a new product category, none of that matters. Apple has sold 3 million of these expensive, limited devices already this year. That really is impressive. And it doesn't matter what date you choose as the starting point.