A Motorola Droid smart phone goes on sale Friday, joining the growing ranks of smart phones on the open-source operating system backed by Google.

With Droid, which will work on the Verizon telecom network, Motorola is taking on mobile devide powerhouses such as Apple, Nokia and Research in Motion (RIM).

"People are gravitating to Android phones because they are different and trendy. Droid may be the new 'in' phone," said analyst Rob Enderle of Enderle Group in Silicon Valley.

Taiwan-based HTC brought the first Android phone to market late last year.

Google chief executive Eric Schmidt recently proclaimed that the smart phone market was on the cusp of an "explosion" of Android devices.

Market tracking firm Gartner agrees, predicting that there will be at least 40 models of Android phones within a year, and that they will be the second place mobile platform by the end of 2012.

Reports surfaced on Thursday that Verizon is poised to add an HTC Android phone to its stable.

"In a few years Android will be the second most popular smart phone running neck-and-neck with Apple," Gartner analyst Van Baker told AFP on Thursday.

Apple iPhones have become coveted devices since they were introduced in early 2007.

Verizon and Motorola have managed to create a marketplace buzz with mysterious video featuring fighter jets releasing metal pods that slam like meteorites into forest, sea, and prairie.

The pods crack open to give glimpses of Droid devices, then end with a cowboy uttering "What in the world is that?" and a message that proclaims Friday the "drop date."

Verizon poked at Apple with 'iDon't' advertising highlighting things iPhones lacks, and US newspapers on Thursday sported full-page ads heralding the Droid's arrival.

Droid devices are likely to pose more of a threat to Blackberry smart phones made by Canada-based RIM than they are to iPhones, according to analysts.

"It's not an iPhone killer," Gartner vice president of mobile computing Ken Dulaney said of Droid.

"This is really about changing the mix at Verizon. It will be some attack on RIM."

Blackberry devices dominate the Verizon network, and the Droid offering will give subscribers a tempting alternative to RIM devices.

Meanwhile, iPhones in the United States are serviced exclusively by telecom colossus AT&T, which has no Android smart phones on its network.

"Droid is not going to draw anyone away from AT&T to Verizon," Dulaney said. "It will keep people at Verizon from going to AT&T and keep some people from going to Blackberry."

US smart phone users get discounted prices on handsets in exchange for signing multi-year service contracts with carriers.

Breaking contracts typically results in hefty fees, a fact likely to discourage people from switching to Verizon just to have Droid phones, according to analysts.

"RIM is likely to get hurt in Verizon and lose a lot of business," Baker said, suggesting subscribers will be lured to Droid handsets while not having to change carriers.

Droid is built with a slide-out keyboards, which appeal to smart phone users prone to typing as is the case with Blackberry devotees, said Dulaney.

RIM is rising to the challenge with the release later this month of a Bold 9700 smart phone.

"The Bold 9700 is outstanding," Dulaney said. "For those that like keyboards it is top-of-the-class."

Blackberry devices appeal to a "different class of user" that likes typing and demands a secure network for taking care of business or other sensitive matters, according to the analyst.

"(US President Barack) Obama is not going to be using iPhone," Dulaney said. "There isn't security in iPhone and Android is a little weaker with support."

Microsoft may end up a victim of Android's success, with the Google software supplanting the Redmond, Washington technology giant's mobile operating system as an industry standard.

"Android is taking the place of what Microsoft wanted to be, the licensed operating system for smart phones," Dulaney said.