Facebook members can soon quit poking, quizzing, and sending useless application requests to one another and begin chatting via instant message.

The social-networking site made the announcement Tuesday, saying the feature would be available in two weeks to the community's estimated 67 million members.

Facebook's move to unleash messaging within its vast audience poses a new challenge to AOL, Microsoft, and other makers of instant- messaging services.

The Palo Alto, California, startup's new chat is not a standalone IM client and requires people to be logged on to Facebook, unlike its competitors. Also, it doesn't allow for conference-style chats.

Facebook’s chat, an imbedded feature within the web site, will likely benefit from its ease of use because it doesn't require a download. This could allow it to better challenge the instant-messaging services offered by AOL, Microsoft, or Yahoo, which require a download.

Sixty-seven million-plus followers represents a pretty good starting point for Facebook's IM launch. That number is one third of the 155 million active users who, according to Microsoft, use the MSN chat.

Facebook’s vice president of product management, Matt Cohler, said during a press conference held at the company’s headquarters on Tuesday that “chat is something we think is part of the core of what’s going on at Facebook.”

Instant messaging is a logical step for a social network, and it is surprising that Facebook waited so long to start its own.

For example, No. 1 social site MySpace started operating its in-house chat, MySpaceIM, nearly two years ago.

As noted by TechCrunch's Michael Arrington, the timing on this certainly is interesting. Yesterday AOL talked extensively about marrying its AIM platform with the company's newly acquired social network Bebo, he wrote.

A number of third-party Facebook platform applications already allow instant messaging between Facebook users. Mr. Arrington said that these developer programs will be killed when Facebook launches its in-house service.

Mr. Cohler disagreed with Mr. Arrington's comment.

“We develop our applications at parity with other developers. Users can remove any of our applications if they want and swap in another feature instead,” he said.

Facebook’s IM was announced yesterday along with privacy measures designed to give users greater control over the information they choose to share.

Facebook is the second largest social-networking web site after MySpace.