should this work or do i need to wait for a new resharper release?
It may work, but I wouldn't count on it. Instead, use the Resharper Preview for VS 2010 (early access program) which is in active development and will remain so until Visual Studio is finalized.
You need to wait for a new release, but there is a preview release specifically for VS2010:
In addition to the previous answers ...
When you think about buying ReSharper - just go ahead:
All ReSharper 4.5 purchases made on or after October 15, 2009, qualify for a FREE upgrade to ReSharper 5.0
ReSharper build 5.0.1526.25 now supports VS2010. Get it form here: http://www.jetbrains.net/confluence/display/ReSharper/ReSharper+5.0+Nightly+Builds
As of today's date (and probably previously), R# 4.5 works with Visual Studio 2010 but is not optimised nor does it include some of the newer features that version 5 uses.
Additionally, you will lose some of those productivity-enhancing keyboard shortcuts if you do not remember which ones you use regularly. Since Visual Studio 2010 has a lot of the features of version 4.5 anyway (auto type inclusion, remove and sort using statements, etc) then there is not much point in using R# 4.5 with it.
I love Resharper but version 5 has a very high memory overhead - which some development machines do not have. 4 gig is a virtual minimum for a machine running the latest VS and R# releases due to the background compiles that R# does.