Yesterday Microsoft released two updates for Internet Explorer 9, including a stability fix for various problems throughout the browser, and another that resolves an issue on 64-bit machines with Windows Live Essentials 2011.
Users with automatic updates enabled will be patched without any action required on their part, any other users who don't should update their Internet Explorer 9 beta now. The first of the two patches is a recommended update for all Internet Explorer 9 users via Windows Update (KB2448827). This update fixes some stability issues in "various scenarios."
The second of the two updates fixes the feedback tool built into IE9. Users running 64-bit machines who also had Windows Live Essentials 2011 installed were unable to run the feedback tool.
Note that this is not an actual build release, but two fixes that resolve issues within the browser, based on user feedback. Microsoft has only released one IE9 beta and 7 platform preview builds thus far.