Geneva is now called Active Directory Federation Services (ADFS).
It is a Security Token Service (STS) which issues signed tokens containing attributes about a user (name, email etc.)
WIF is the set of classes you include in a ASP.NET application that provides the plumbing to connect to ADFS.
Have a look at:
A Guide to Claims-Based Identity and Access Control
Windows Identity Foundation (WIF) Content Map
Update
The WIF link above contains a link to Get Started with Windows Identity Foundation (WIF) which includes the Identity Training Kit and some "Getting Started" examples.