Article updated at 4:35 p.m. PT with more information from Google's official announcement.
Starting Thursday, iPhone users surfing to m.google.com/latitude can access Google Latitude, Google's friend-tracking feature. Latitude plots friends' pictures on a Google map when they opt to share their location with you.
Earlier this morning, some CNET employees were able to start experimenting with Google's Web-based Latitude for iPhone ahead of the official announcement.
Once loaded, Latitude becomes a tab on m.google.com, Google's mobile face.
The main interface presents a list of contacts. Clicking on your own icon lets you set your status and edit your privacy settings.
Clicking a contact's icon presents the option to send an e-mail, get directions to the contact's location, and change the precision of location information you'd like to share with the person. The options are "best available location," "only city-level location," and "hide from this friend."
The three privacy options let you set the application to detect your location automatically, to require you to set it manually, and to hide your location altogether.
The Web app integrates with the Gmail contacts list, letting you select contacts you'd like to invite from the list; those who already are Google Latitude users get a special icon to let you know they're signed up already. You also can invite people by their e-mail addresses without using Gmail contacts.
In addition to tracking friends, the menu supplies options to search or clear the map, view traffic, get directions, and see a satellite view.
Before Google announced Latitude for iPhone, we surmised that the Latitude feature is meant as an upgrade--or at least as an alternative--to maps.google.com for iPhone users. In a statement, Google explained that the company worked closely with Apple to create the Latitude experience that works around Apple's inability to run apps--even browser-based--in the background. Google gets around this by updating location when you launch the app, and while it runs in the foreground.
Google's Latitude Web app runs on iPhone operating system 3.0. It is currently available in Australia, Canada, New Zealand, and in the U.K., and U.S.