The GenericUserFolder is a roll-your-own user folder. It provides hooks so you can easily customize your Zope authentication system to work the way you need.
This product is being deprecated in favour of more modern products such as SimpleUserFolder and exUserFolder. SimpleUserFolder is the most similar in design and scope to GUF, while exUserFolder is a larger and more ambitious project that aims to provide more out of the box functionality.
out of the box
GUF is a finished product and no longer being updated. Most available documentation was written for Zope 2.2, and this product is known to work with Zope 2.3. I don't believe it will work with Zope 2.4 or later.