You can use any version of Inventor for the Autodesk Inventor Award submission which can create the required .DWF files (Inventor 9 can do this). Inventor 10 has a lot of new features, but I don't see any reason one couldn't build a winning entry with the earlier releases - it might just take a little more work.
As for the Virtual Kit of Parts (aka VKoP), it is in Inventor 10 so these models will not open with earlier versions. The only solution for those using pre-v10 is to get the files translated (Save As...) to STEP format which will open with the earlier versions.
Many of the parts in the kit are the same as last year, and you should be able to find models of them in Inventor 8 or earlier at:
IFI
FIRSTCADLibrary