Windows 8.1 (blue) Released and you can update it for free if you are using a genuine copy of Windows8 You can Update it for free using Microsoft Update Assistant.
Microsoft in a official blog post said :
"Today at the JP Morgan Technology, Media & Telecom Conference in Boston, Tami Reller shared with the audience that the update previously referred to as “Windows Blue” will be called Windows 8.1and will be a free update to Windows 8 for consumers through the Windows Store."
Windows 8.1 will be rolled out for Normal people on 26 june , However Dev preview is available for developers
Microsoft also stated that its Store has crossed a 70,000 application mark which is remarkbley high within such a small time.
If you happen to be one of the small number of users who have a Windows RT device like Surface RT, we're sure you'll be thrilled to know that the Windows 8.1 update will also be coming to your device.