Microsoft almost lists Windows Phone 8.1's features on its website
Either by mistake, or as a tease, Microsoft is now listing Windows Phone 8.1 next to Windows Phone 8 on the platform’s official website. Unfortunately, if you click the WP 8.1 link, which should lead to the “top features” of the OS, all you’re getting is a “Not found” page.
Microsoft could release Windows Phone 8.1 in April, after its Build Conference that takes place between April 2 and April 4. New hardware will likely appear at about that time, too, possibly not just from Nokia. But we’ll see what happens.
Update: The "Windows Phone 8.1" reference was removed by Microsoft today. So maybe this was a mistake after all.
source: Windows Phone via WPCentral
Things that are NOT allowed: