The roadmap for Tegra is not covered in a shroud of secrecy with nVidia pushing for a one year life-cycle unlike the current competition which prefers longer lead times. There are two generations in the works, with design papers being written for generations to come. NVidia is trying to have a next generation of Tegra debuting on first day of Mobile World Congress. In case of T2 and T3 [codenames for Tegra Gen2 and Gen3], the parts should debut on February 15th, 2010 and February 14th, 2011.
The second generation Tegra part will offer a 400% performance increase in terms of performance. While this "performance increase" is not specified, we know that the company will utilize parts that are designed for TSMC's low-power process. Thus, you can expect to see a next-gen ARM core [Cortex instead of ARM11] in a dual-core form, and a GPU subsystem based on the GeForce 9 architecture. We expect that nVidia will tout CUDA and OpenCL compliancy with the Tegra Gen2. Don't even get started with Tegra Gen3 - the GPU on that will be more than a beast.