Marc McKechnie, an analyst with Broadpoint AmTech, told news media that most of Verizon's retail outlets sold more than half their inventory, and some were nearly sold out. Verizon reportedly had 200,000 units for sale, but hasn't made any official comment on sales figures.

The 'iDon't' Droid

By comparison, Apple reported it sold more than one million units of the iPhone 3GS during its launch weekend in June.

Verizon is the exclusive carrier in the U.S. for the Droid, which uses Google's open-source Android operating system, and its aggressive "iDon't" ad campaign has been touting the things the iPhone doesn't have but Droid does.

"iDon't have a real keyboard," the ad said, touting other "iDon't" shortcomings of the iPhone. The ad, which ran extensively on TV and in print, ends with "Everything iDon't ... Droid Does."

Verizon is trying to counter a recent net gain of 800,000 new customers by rival AT&T, the exclusive iPhone carrier in the U.S., although Verizon still leads in the total number of mobile customers. AT&T's customer boost has been seen by industry observers as largely due to the iPhone.

Motorola is looking to the Droid and Android-based devices to boost its falling market share, which stood at 4.7 percent last quarter, compared to the second quarter's 5.5 percent. McKechnie has predicted that Motorola will sell a million Android-based phones in the fourth quarter, including the Droid, and another 10 million next year.

Droid 'Doing Fine'

Only a handful of phones on the market use Android, but the number is expected to increase rapidly in the next few months. Android is also beginning to appear on netbooks, tablet computers, and other devices.

Like the iPhone, the Droid is a touchscreen device with an engaging interface. The smartphone has been getting good notices, with some reviewers calling it the most impressive phone since the iPhone.

The Droid also has a slide-out keyboard, a higher-resolution camera, application multitasking, and Verizon's 3G network. Besides the Apple cachet and its unique user interface, the iPhone has more than 10 times as many applications, which are increasingly becoming a factor in consumer purchase decisions.

Avi Greengart, an analyst with industry research firm Current Analysis, said he doesn't know the exact number sold, but "from what I've seen and from talking to retailers, I'd say the Droid is selling briskly."

He noted that, anecdotally, "a lot" of retailers are close to selling out. Until we get an actual number, Greengart added, "it's hard to tell exactly." But, he noted, "relative to my expectations, it's doing fine."