We were waiting it for so long and now it happened!
JetBrains published first public available build of ReSharper for Visual Studio 2010. You could get it from EAP download page.
Note that it is a preview:
ReSharper for Visual Studio 2010 (preview) - is an early build for those who are trying out Visual Studio 2010 and cannot live without ReSharper. It is neither 4.5.1 for VS10, nor 5.0 for VS10. It is intermediate result of our attempts to integrate with Visual Studio 2010 extensibility model, plus preliminary state of some of ReSharper v5 features (you will find some of them enabled). Complete roadmap for ReSharper v5 will be published soon.
Of cource there are still 79 blocker issues in the Bug Tracking database. But you have a greate chance to be the first public beta tester 