The G1 smartphone, produced by Taiwan’s High Tech Computer (HTC) Corporation, and using Google’s Android mobile operating systems went on sale Tuesday evening in San Francisco, in anticipation of its Wednesday nationwide release.

A line of about 150 people waited eagerly for 6.pm in front of the T-Mobile store on Market Street, to be the first ones to buy the $180 phone.

The 3G enabled smartphone is the first of several upcoming handsets running the Android operating system, and is a serious contender for other smartphones like the Apple iPhone or the BlackBerry, combining strongpoints of both with scalable, customizable software and the possibility to download applications from an online store, much like the former; and a slide-out QWERTY keyboard in addition to its touch screen like the latter.

The keyboard should appeal to those users which aren’t comfortable with the virtual touch keyboard input method on the iPhone, but who still would like to enjoy a large display and the use of a touch-screen for other interface elements. Its array of features is no throwaway either, with a 3.2 inch display, full media support, Bluetooth, EDGE, Wi-Fi, 3G, a (still) camera, GPS, a compass and an accelerometer.

The HTC G1 will be available for $179.99 with a two-year service agreement and a mail-in rebate, or optionally for around $400 to buy the phone outright and waive the service plan.

Initial reviews of the phone have been positive, with most evaluations regarding it as a worthy competitor to the iPhone, even if it does lack some of Apple's signature style.

In addition, it offers features that the iPhone lacks, such as a keyboard, removable battery, SD card slot, a better camera and the ability to run several programs at once. It also makes using Google products such as Gmail, Maps and Calendar easy to use.

The G1 will be sold outside the United States later this year, starting with Europe, where the carrier T-Mobile has an established presence.