Windows 7

"Microsoft accidentally put up a page saying that the RC will be released on May 5th earlier this week. However, wzor.net suspects that it will be publicly released after Microsoft’s TechEd event on May 15th. Windows 7 Center will keep you posted on when the official RC comes from Microsoft."

source: http://windows7center.com/news/windows-7-rc-download-build-7100-x86-and-x64-leaked/