http://sharepoint.microsoft.com is built on top of SharePoint!
Found via SharePoint Detector.
Ever wondered whether a site is built on top of SharePoint? Now, there is an easy way to find out. Install the “SharePoint Detector” Chrome extension located at https://chrome.google.com/extensions/detail/iglddabgpnbmcpdnmcbhhmggipakapck?hl=en, and you will get the SharePoint icon displayed in Chrome’s address bar every time you browse to a SharePoint site. You can then click on the SharePoint icon and choose to share the site by email, on your WordPress blog, LinkedIn, Twitter, Facebook and\or StumbleUpon.
For example, here is what happens when you browse to http://www.wssdemo.com.
If you decide to share on Twitter, you will get the following popup.
You can edit it as you like then post to your Twitter account. Same goes for all the other different methods of sharing..
Enjoy sharing SharePoint!