Tegra 2 is a system-on-a-chip (SoC) created by NVIDIA. The SoC comprises a dual-core ARM Cortex-A9, an NVIDIA ultra low power (ULP) GPU, an ARM A7 and five other processing cores for audio and video processing.
The NVIDIA developer zone has more information on Tegra at: 
There are forums for software developers and the like at 
- Tegra 2 Chip
- Tegra 250 Development Board
- Operating Systems
- OpenGL Information and Development