Early on at the 2011 Mobile World Congress, Samsung and NVIDIA made an announcement that the Galaxy Tab 10.1 will be made with NVIDIA's Tegra 2 SoC (I9103). They also announced that they would be working on a new superphone based on Tegra 2. But at Samsung's press conference, we saw the Galaxy Tab 10.1 and the Galaxy S II, using Samsung's Exynos SoC (GT-I9100). There was no mention of NVIDIA or Tegra 2. Why would Samsung use Tegra 2 when it already has a Exynos-based smartphone?
Samsung sold 10 million Galaxy S phones in 2010, and they are probably on track to sell at least that many Galaxy S II phones once they are available. And Exynos is a brand new SoC, with a brand new GPU for Samsung that Samsung has never shipped. This may be risky, considering the demand that Samsung is facing in markets around the world.
NVIDIA's Tegra 2 is nearly equivalent in CPU performance, and better in GPU and Flash performance (see the benchmarks posted by AnandTech yesterday), so it is a pretty good alternative to the Exynos SoC.
Samsung listed its own dual-core Application Processor in the Galaxy S II as not being used in all regions, which may mean that Samsung could choose to use Tegra 2 or Exynos depending on the region.