AOL is providing the newest communications channel on Google.

Fulfilling a pledge made two years ago, Google Inc. this week unveiled a feature that enables people to chat on AOL’s instant messaging service through “Gmail” - the popular search company’s free e-mail service.

Not all Gmail users can get at the instant message service yet because Mountain View-based Google is still rolling out the coding that includes the settings to log on to AOL instant messaging, or AIM. Google officials didn’t set a timetable for making AIM available to all its Gmail users.

It took a long time to get this far. Google first disclosed its plans to open its doors to AIM in December 2005 when it paid $1 billion for a 5 percent stake in Time Warner Inc.’s AOL.

But the plan went on the back burner while Google engineers worked on myriad other projects, said Mike Jazayeri, a senior product manager for Google.

Meanwhile, rivals Microsoft Corp. and Yahoo Inc. last year cross-pollinated their instant messaging services.

Adding access to AOL’s instant messaging service may help Google attract more people to its e-mail service, which has been gaining ground on its larger rivals.

The Oak Ridge National Laboratory revealed on Thursday that a “sophisticated cyber attack” over the last few weeks may have allowed personal information about thousands of lab visitors to be stolen.

The assault appeared “to be part of a coordinated attempt to gain access to computer networks at numerous laboratories and other institutions across the country,” lab director Thom Mason said in a memo to the 4,200 employees at the Department of Energy facility.

Oak Ridge officials would not identify the other institutions affected by the breach. But they said hackers may have infiltrated a database of names, Social Security numbers and birth dates of every lab visitor between 1990 and 2004.

“There was no classified data of any kind compromised,” lab spokesman Bill Stair said Thursday. “There are people who think that because they accessed this database that they had access to the lab’s supercomputer. That is not the case. There was no access at all.”