"Whether it's used in business, friendship or romance, Instant Messaging has swept the nation to become an essential part of day to day life," said Mark West from the Windows Live Messenger team, in a statement.
"This is a real milestone for Windows Live Messenger and we're very excited to see what the next 10 years has in store."
Indeed, there is no question that instant messaging has changed the face of both personal and business communications.
Many business users are expecting their in-work use of IM to increase in the coming years.
There is even talk that IM may replace email as the primary method of mobile communication.
"Windows Live Messenger might have started out as a consumer application, but it quickly found a home in businesses," John Cunningham, ntl:Telewest Business' director of business markets, added in a statement.
"It has driven the requirement for instantaneous communication - whereas people used to have to wait, they can now expect an immediate reply."
To celebrate the IM milestone, Microsoft has installed a giant interactive messenger in a bottle that lets visitors chat and play games with people around the world and perhaps even a celebrity or two - at Potter's Fields, near Tower Bridge.
It was officially opened' by former Blue Peter presenter Konnie Huq.
