Just in case you have missed or ignored the downloads on 3rd party sites, now they are official:
Hair (http://download.nvidia.com/downloads/GeForcecom/techdemos/HairStandaloneFermi.zip)
Island (http://download.nvidia.com/downloads/GeForcecom/techdemos/island11_new.zip)
Grass demo has not yet been released :-\
D3D11/SM5 GPU mandatory, don't try these demos with older GPUs.