Email has had a good run as king of communications. But its reign is over.

So begins a supposedly provocative article published in the Wall Street Journal today. Jessica E. Vascellaro writes in “Why Email No Longer Rules..” that email is now taking a backseat to real-time, constantly updated forms of communication provided by services like Twitter, Facebook, and soon, Google Wave, services that an exec at AOL says replace the in-box with “a river that continues to flow as you dip into it.” She backs up the assertion with a surprising stat:

In August 2009, 276.9 million people used email across the U.S., several European countries, Australia and Brazil, according to Nielsen Co., up 21% from 229.2 million in August 2008. But the number of users on social-networking and other community sites jumped 31% to 301.5 million people.

Did Vascellaro just say more people use social networks than use email? Sure seems like it. I’m not too sure how those numbers were arrived at, but I’ll take Nielsen’s word for it. I know there have to be plenty of grandmas out there who only use a computer to check on pics of their grandkids, and there are probably plenty of kids out there who use Facebook as their primary email account. Still, I don’t see email going anywhere any time soon. And neither does Vascellaro. Private communication will always be the most important form of communication.

According to data provided by AddToAny, the popular widget that provides websites with a link-posting service that functions across multiple platforms, Facebook is now by far the most popular way for users to share stories and information with their friends. It would appear that the social aspect - the ability to have content seen by a larger network all at once and host a conversation - is certainly fueling this trend.

As noted by the Business Insider, Twitter is already nearly half as popular as Facebook, but with only one tenth of the users.

This overall shift seems to follow what many are hailing as the web’s next revolutionary innovation, “Social Search” which I recently wrote about on my website here.

Facebook recevied a cool $200 million from Russian investment group Digital Sky Technologies in exchange for a 2% stake, making the company’s valued net worth $100 billion.  Notably, just one year ago the company’s internal valuation was $3.7 billion.  It will be interesting to see where Facebook takes its business in the future, as Microsoft paid $240 million for a 1.6% stake in 2008.