Apple just announced it sold over 300,000 iPads on Saturday, lower than analyst estimates of 700,000 (that was for the whole weekend, but the bulk undoubtedly came on Saturday), but more than the estimated 270,00 iPhones sold in the first weekend in 2007.

Some think the comparison to iPhone sales is unhelpful. I disagree. The iPhone fell into a device category the world was familiar with: cell phones. Every tech pundit on the planet talked about the need for a PDA that could handle web browsing elegantly. The iPhone filled a whole in the market and deserved to sell like crazy.

Not even Steve Jobs himself thought the world needed a tablet before the iPad. No one knew what to use them for until Jobs sat leisurely in a couch up on stage in January, swiping through pictures, creating a new kind of past time. The fact that more people turned out to purchase a more expensive device that no one needed a few months ago says a lot about Apple’s ability to create a market.

The numbers look even more impressive, given that initial sales represent the U.S. only, and just the Wi-Fi model. Many early adopters are waiting for the 3G-capable iPad to go on sale in the U.S. later this month.