5:36 p.m. | Updated to add that Zillow is also planning apps for Glass.
Walk down a street wearing Google Glass, and you can see alerts about nearby houses on the market.
The alerts are courtesy of Trulia, the real estate site, which this week introduced an app for Google Glass. It is one of only a handful of apps available for the Internet-connected glasses, and is an example of how software developers are experimenting with the new device.
Trulia’s app sends alerts for houses that the service thinks users want to see, whether because of criteria they have previously given Trulia or because of the types of houses in which they have shown interest. On Google Glass, people can scroll through photographs, get walking directions to a house, hear a description, save a listing to an account and call or e-mail a real estate agent.
Like Yelp or Google Maps, real estate sites like Trulia are an example of services that are often more helpful on mobile devices than on computers, because people use them to learn more about their current location. More than half of weekend traffic and a majority of leads for real estate agents come from mobile devices, according to Trulia.
But the app raises the question of whether people want to see the information pushed to a screen in front of their eyes.
“The model is different,” said Jeff McConathy, vice president for engineering for consumer services at Trulia, who built the Glass app during two weekends. “When a person engages with a phone, they express intent. With Glass, you have to be very careful that you’re not being intrusive.”
He said that the Trulia app for Glass shows “tiny tidbits so as not to overwhelm,” and that it works well on the format because it is reliant on location and photos.
Zillow, another real estate site, is also preparing apps for Glass. Users will be able to see information on when a house was last sold, compare that with its current estimated price and see photos, said Rich Barton, Zillow’s co-founder. Like Trulia, the Glass apps will connect customers with real estate agents, which is one way both companies make money.
Building apps for Glass, known as Glassware, is a still a gamble for developers. No one wants to miss out on the next big thing, but there is no guarantee that Glass is it.
Mr. McConathy said that building the app felt like the early days of experimenting with building iPhone apps, but that he was not yet convinced that Glass is the form of the future. He has been wearing it for a few weeks and said he used it mostly to read the time, which is on the home screen, or to read text messages while he is riding his motorcycle.
Only a couple thousand people who have signed up with Google have Glass, and there is not yet a public app store. Only people who own the device have full access to the tools to build apps and the ability to download new ones, and only after Google approves the apps.
Quentin Hardy contributed to this post.