Stellaris LM4F120 Series: What happened to it?
The Stellaris LM4F120 LaunchPad is still available at the Texas Instruments eStore, but not for long. It is in the process of being replaced by the rebranded "Tiva C" series.

The user manual for the LM4F120 Launchpad evaluation board is still available, as is the StellarisWare software. However, the datasheets for the LM4F120 ARM processors have vanished from the site. The new TM4C123 replacements are apparently not identical.

The new Tiva C LaunchPad is available for pre-order, with 8 to 10 weeks to delivery.

This is probably one of the worst-orchestrated product phase-out / replacement exercises Texas Instruments has ever done - Even the shakiest manufacturers rarely remove the datasheets and other documentation for discontinued or replaced products, and TI has typically been pretty dependable.