There are numerous ways to broadcast your location with a smartphone.

Redmond startup Glympse is joining the fray, but with a twist: Glympse lets users temporarily invite friends, family or contacts to track their whereabouts. The time limited sharing of location data is a key difference from services such as Google's Latitude.

Once the service is installed on a phone, users can click on a contact to send a "glympse" message. The recipient can then see the sender's location displayed on a map. The location transmission can be limited to a few minutes, or provided for up to four hours.

Initially the service is available only on T-Mobile USA G1 phones, based on the Android operating system backed by Google, but Glympse plans to "soon" be available on the iPhone, BlackBerry and Windows Mobile devices.

The idea is to help people share location information easily and with more control, Glympse Chief Executive Bryan Trussel said in the release.

"In reality there are very few people who we want to know where we are all of the time; yet, there are lots of people who we want to know where we are some of the time,'' he said. "Only Glympse offers the ability to share your location with exactly whom you want, for exactly how long you choose."

Glympse was founded in March 2008 by three ex-Microsoft developers -- Trussel, Jeremy Mercer and Steve Miller -- who worked on embedded systems, games, Windows and interactive TV. They funded the 10-person company, along with unnamed angel investors.

Trussel is unveiling the service at the Web 2.0 Conference's Launchpad event Tuesday in San Jose, Calif.

Glympse will be free initially, while the company builds scale. The company expects to eventually make money from ads, premium services and versions for business.