Who is buying new Apple ( AAPL) iPhone 3Gs? According to comScore, the answer is everyone.

ComScore's digital media analysts say 43% of iPhone owners earn more than $100,000 a year, but the real treasure trove that Apple is tapping is buyers who earn less than the median household income.

According to comScore:
iPhone adoption since June rose 48 percent among those earning between $25,000 and $50,000 per year and by 46 percent among those earning between $25,000 and $75,000. These growth rates are three times greater than that of those earning more than $100,000 per year. Overall, iPhone penetration grew 21 percent.

Those are great numbers by any standards -- and especially impressive considering that though smartphones such as Research in Motion's ( RIMM) BlackBerry and various offerings from Palm ( PALM) have been around for a decade or so, they're only now becoming popular with consumers.

Mark Donovan, senior analyst for comScore, reminded me that the cellular industry is undergoing huge change, with users flocking toward smartphones, and especially to the second-generation iPhone.

According to comScore:
The number of people earning between $25,000 and $50,000 accessing news and information via mobile browsers grew by five percent since June, while the market overall grew by three percent. There has also been seven percent growth in mobile e-mail usage and five percent growth in mobile music consumption among that income group.

"These data indicate that lower-income mobile subscribers are increasingly turning to their mobile devices to access the Internet, e-mail and their music collections," wrote Donovan. "Smartphones, and the iPhone in particular, are appealing to a new demographic and satisfying demand for a single device for communication and entertainment, even as consumers weather the economy by cutting back on gadgets."

Super marketing, great timing and word of mouth all contribute to the iPhone's overwhelming success.

According to Senior Analyst Jen Wu: "As an additional household budget item, a $200 device plus at least $70 per month for phone service seems a bit extravagant for those with lower disposable income. However, one actually realizes cost savings when the device is used in lieu of multiple digital devices and services, transforming the iPhone from a luxury item to a practical communication and entertainment tool."

Donovan told me that even in a slow economy consumers are increasingly interested in carrying a single "Swiss army knife" type of a device that includes a still/video camera, iPod music and video player, Web browser and, of course, a cell phone. He called this a "shift of the center of gravity" toward these versatile products. And buyers especially like what they see from Apple's "ecosystem" of products.

He added that the iPhone's $200 selling price doesn't hurt either.

Finally, I asked if large iPhone sales might put a dent in iPod sales, and Donovan said it really didn't matter. The bottom line was that consumers were still spending their money on Apple products.
Gary Krakow is TheStreet.com's senior technology correspondent.