No, not yet. The current plan is for it to be included in the Windows 7 Release Candidate later this year:

Windows 7 Beta already includes a pre-release candidate version of Internet Explorer 8 that is optimized for that release. 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. We will continue to update the version of Internet Explorer 8 running on Windows 7 as the development cycles of Windows 7 progress and plan to include the final version of Internet Explorer 8 in the release candidate version of Windows 7 later this year. For the latest information on Windows 7, visit the Windows 7 site. [This quote from the Internet Explorer 8 site.]