Yahoo is working on a mobile service called oneConnect designed to aggregate contacts and communications around what it calls a "socially connected address book."

The service, due to launch in the second quarter this year, draws information from social-networking sites such as MySpace, instant-messaging services such as Yahoo Messenger or AOL Instant Messenger, and email services including Yahoo Mail and Google's Gmail to build a picture of the mood, location and activities of friends and colleagues.

It also stores details of recent communications with address-book contacts, including instant-messaging and e-mail exchanges. All the information held about a person can be viewed on a "social contact card."

Location data is calculated by GPS in handsets that have it, or deduced from nearby cell tower locations. Users of the service can keep their locations private, or opt to share that information with others.

Combining all the information gathered by the service allows Yahoo to alert users of the service when friends arrive in town, or to let them follow up on unfinished business when colleagues become available.

"I can see all my communications archives so when someone comes up to me, I know whether I answered his last email," said Marco Boerries, executive vice president of Yahoo's Connected Life division.

Yahoo oneConnect is built on the same widget platform that Yahoo used for its oneSearch mobile search service, so it will work on some 300 phones, either in a browser, as a Java applet or as a native application.

Boerries said that oneConnect could extract information about the status and activities of members of a social network on other services such as MySpace.

With some of those services, he said, Yahoo developed the code to exchange the information, while other partners chose to develop the bridge themselves. "We don't want to be competing to build a better Facebook client," he said.

In one case, though, the intervention of a neutral party was necessary to get both sides talking. Although oneConnect can collect information from Microsoft Exchange email accounts, the connector was written by Dataviz, a third-party software developer specialising in data translation. Microsoft recently made an unsolicited offer to purchase Yahoo, and the two companies are engaged in a war of words over the value of the bid, which may turn hostile.

Opening up the social network to other services will allow Yahoo to bulk up in its battle with Google for the attention of Internet users. But Google is also a potential partner for the service: the beta version of oneConnect gathers information from Google Talk and Gmail.

The service sends large amounts of data to and from the mobile phone making the service potentially expensive to use. Boerries acknowledged that data rates could be a problem, adding that Yahoo is negotiating with operator partners to introduce all-inclusive data tariffs for the service. In return, those partners could benefit from a share of the advertising revenue generated by Yahoo's online services, he said.