Ivan just IM-ed me with a link: http://www.jetbrains.net/confluence/display/ReSharper/ReSharper+4.0+Nightly+Builds
I've been waiting for a C# 3.0 compatible version since I installed VS2008 back in December: apparently it has been announced by Ilya Ryzhenkov on his blog yesterday but I didn't get the news till now. Here are the release notes.
I'm going to install it: it will not do much harm and if anything goes wrong I can always turn it off as I'm already doing now with the 3.1 since it marks everything "new" as error. I hope it will support also Silverlight project and will not mark variables defined in the XAML as not defined.
PS: I just noticed that Steve announced this as well.