Apple continues to see success in the smartphone market, as its iPhone 3G S sold more than a million units during its launch weekend.

The company has launched a touch-screen smartphone each of the last three summers, and it appears to be picking up momentum with each release. The iPhone 3G S was generally expected to sell well, but not as well as the iPhone 3G, which also sold a million units during its debut weekend last year.

"Customers are voting and the iPhone is winning," Apple CEO Steve Jobs said in a statement. "With over 50,000 applications available from Apple's revolutionary App Store, iPhone momentum is stronger than ever."

The new handset was seen as an evolutionary, rather than revolutionary, upgrade of the iPhone lineup. Apple said it's the fastest, most powerful iPhone yet, and it has a beefier processor and more RAM, and is capable of faster mobile data connections than previous versions.

One of the most well-received features of the iPhone 3G S is the improved camera, which now has 3.2 megapixels and an auto-focus feature. The handset also can record videos at 30 frames per second, which can be edited on the handset and uploaded to YouTube with one click.

The sales success of the iPhone 3G S is particularly impressive considering there were a few roadblocks for customers coming from AT&T and Apple. Many iPhone 3G subscribers weren't eligible for the $199 and $299 price points, and may have had to pay a $200 premium. Additionally, Apple lowered the price of the iPhone 3G to $99 and released an updated firmware that adds existing functionality to existing iPhones.

InformationWeek has published an in-depth report on smartphone security. Download the report here (registration required).