Windows 7 support is crucial for Microsoft, given there are more than 700 million Windows 7 users out there, according to the company. (In comparison, there are currently more than 100 million copies of Windows 8 that have been licensed, last we heard from Microsoft.)
The IE11 for Windows 7 developer preview is available for download today. The new developer preview also works on Windows Server 2008 R2. (Download center links are here, as well.)
IE11 for Windows 7 includes many, but not all, of the same features that are in the Windows 8.1 version, which is currently in public preview.