电子邮件的时代是否已经过去

'The whole idea of this email service isn't really quite as significant anymore when you can have many, many different types of messages and files and when you have this all on the same type of networks,' says Alex Bochannek, curator at the Computer History Museum in Mountain View, Calif.

So, how will these new tools change the way we communicate? Let's start with the most obvious: They make our interactions that much faster.

Years ago, we were frustrated if it took a few days for a letter to arrive. A couple of years ago, we'd complain about a half-hour delay in getting an email. Today, we gripe about it taking an extra few seconds for a text message to go through. In a few months, we may be complaining that our cellphones aren't automatically able to send messages to friends within a certain distance, letting them know we're nearby. (A number of services already do this.)

These new services also make communicating more frequent and informal -- more like a blog comment or a throwaway aside, rather than a crafted email sent to one person. No need to spend time writing a long email to your half-dozen closest friends about how your vacation went. Now those friends, if they're interested, can watch it unfold in real time online. Instead of sending a few emails a week to a handful of friends, you can send dozens of messages a day to hundreds of people who know you, or just barely do.

Consider Twitter. The service allows users to send 140-character messages to people who have subscribed to see them, called followers. So instead of sending an email to friends announcing that you just got a new job, you can just tweet it for all the people who have chosen to 'follow' you to see. You can create links to particular users in messages by entering @ followed by their user name or send private 'direct messages' through the system by typing d and the user name.

Facebook is part of the trend, too. Users post status updates that show up in their friends' 'streams.' They can also post links to content and comment on it. No in-box required.

Dozens of other companies, from AOL and Yahoo Inc. to start-ups like Yammer Inc., are building products based on the same theme.

David Liu, an executive at AOL, calls it replacing the in-box with 'a river that continues to flow as you dip into it.'

But the speed and ease of communication cut both ways. While making communication more frequent, they can also make it less personal and intimate. Communicating is becoming so easy that the recipient knows how little time and thought was required of the sender. Yes, your half-dozen closest friends can read your vacation updates. But so can your 500 other 'friends.' And if you know all these people are reading your updates, you might say a lot less than you would otherwise.

Another obvious downside to the constant stream: It's a constant stream.

That can make it harder to determine the importance of various messages. When people can more easily fire off all sorts of messages -- from updates about their breakfast to questions about the evening's plans -- being able to figure out which messages are truly important, or even which warrant a response, can be difficult. Information overload can lead some people to tune out messages altogether.

Such noise makes us even more dependent on technology to help us communicate. Without software to help filter and organize based on factors we deem relevant, we'd drown in the deluge.

Perhaps the biggest change that these email successors bring is more of a public profile for users. In the email world, you are your name followed by a 'dot-com.' That's it. In the new messaging world, you have a higher profile, packed with data you want to share and possibly some you don't.

Such a public profile has its pluses and minuses. It can draw the people communicating closer, allowing them to exchange not only text but also all sorts of personal information, even facial cues. You know a lot about the person you are talking to, even before you've ever exchanged a single word.