Requires PowerShell 2.0 RTM
The functions in the attached ps1 script are the bare minimum for a working container-style provider (no subfolders.) The demo lets you navigate the data represented in the $data hashtable with a "PS" drive. Keys are first-level paths in the container, values are the items at these paths. This is just a proof of concept; future release roadmap on the home page.
Rename the below .txt file to .ps1 and open in it your favourite PowerShell Script Debugger (e.g. Windows PowerShell ISE.) and place breakpoints with F9, hit F5 to run.