The percentage of adults who own mobile phones now matches the percentage who own computers, says Pew in a study released today. And more than 80 percent of them say they use voice calls to share their location. That may be good news for startups such as Foursquare, which is a mobile application that lets users display their location to friends, because it shows people want convenient ways to coordinate meet-ups.

Some 45 percent of mobile phone users call to check in, or to check someone's location daily, according to the survey of 2,252 U.S. adults conducted in April and May. The activity is only second to calling to just say hello and chat, done by 48 percent of the respondents daily.

The study also discovered that U.S. mobile phone users like to keep their handsets close by at night. Two-thirds of American adults sleep with their phone right on or next to their bed. Heavy texters are more likely to sleep next to their phone, and the numbers of those users are on the rise. An average user sends and receives 10 texts a day, up from five text messages just eight months ago, the study found. Some 72 percent of adults 18 and over with cell phones send and receive text messages, up from 58 percent surveyed in December of 2007.