It's not a hoax at all. It's true - the archive really exists, and seems very complete.
Actually it looks to contain all the core stuff, including the Explorer etc.
Personally I don't think it will have many consequences to the virus arena, though... 99.99% of viruses use holes that have already been discovered by someone else -- relying on the fact that there are many people who don't apply the patches.
To find a new buffer overflow, even with source code, is not an easy task...