Microsoft yesterday quietly released what is being described as a release candidate version of Internet Explorer (IE) 8. This pre-release version is essentially the final form of IE8 but MS officials declined to reveal when the official launch will be.

Among the highlights of IE8: The addition of private browsing, enhanced security and a new class of add-ons MS is calling accelerators.

IE8 will be compatible with Windows Vista and later versions of Windows XP (with Sevice Pack 2).

Curiously, IE8 General Manager Dean Hachamovitch notes that Windows 7, still officially scheduled for release later this year, will ship with the “release candidate” version of IE8.

In a prepared statement, MS explained, “Windows 7 enables unique features and functionality in Internet Explorer 8 including Windows Touch and Jump Lists which require additional product tests to ensure we are providing the best Windows experience for our customers. Microsoft will continue to update the version of Internet Explorer 8 running on Windows 7 as the development cycles of Windows 7 progress.”

If you want to try the release candidate version of IE8, it’s available now at the MS Download Center.