I saw this first on Sophos blog linked above.
Cut and paste from NVIDIA's warning post below, see their link for complete message, http://www.nvidia.com/content/devzone/index.html,
NVIDIA suspended operations today of the NVIDIA Developer Zone (developer.nvidia.com). We did this in response to attacks on the site by unauthorized third parties who may have gained access to hashed passwords.
We are investigating this matter and working around the clock to ensure that secure operations can be restored.
As a precautionary measure, we strongly recommend that you change any identical passwords that you may be using elsewhere.
NVIDIA does not request sensitive information by email. Do not provide personal, financial or sensitive information (including new passwords) in response to any email purporting to be sent by an NVIDIA employee or representative.
For more on Passwords see More D3 Account Security or Computer & Password Security: Salting & Hashing explained clearly or Steve Gibson's Haystacks & Needles (Understanding Passwords).