Internet Explorer 10 is available worldwide for download (at http://windows.microsoft.com/en-us/internet-explorer/download-ie) since February 26 2013. Microsoft will distribute Windows Internet Explorer 10 as an important update through Automatic Updates for Windows 7 SP1 and higher for x64 and x86 and Windows Server 2008 R2 SP1 and higher for x64.
Please note, that if you update to IE10, your backend release has to fulfill the minimum Service Pack Stack requirement:
NetWeaver 7.00 SPS27
NetWeaver 7.01 SPS13
NetWeaver 7.02 SPS12
NetWeaver 7.03 SPS05
NetWeaver 7.30 SPS08
NetWeaver 7.31 SPS05
Otherwise you have to set the Compatibility mode of IE manually, as IE10 changes the default rendering behavior.
You may also use the Microsoft toolkit to disable automatic delivery of Internet Explorer 10, if you are on a lower backend SP stack.