Ironhide
From Hybridgraphics
This is the most recent implementation of the original bumblebee code written by Martin Juhl.
It installs and configures the ACPI calls to switch the discrete graphics card on/off via acpi_call, and provides a graphical user interface to set up the system to each specific laptop configuration.
Available here: http://github.com/MrMEEE/ironhide