I just had a stroke of insight... or maybe just a stroke -- who knows.

Anyhoo... I was watching this video of the Tab 8.9/10.1 unveiling, and I noticed that the units animation was quite jerky. This is likely because it's an early build.
http://www.youtube.com/watch?v=5q_B3PBO1cI

Here's the interesting bit. The Tab 10.1 circa Feb 13, which was using the Tegra 2 ran much more fluidly. This may imply that the hardware running on the 8.9" prototype wasn't Tegra 2, and likely the drivers were very early.

Now, if true, this doesn't mean that a Tegra 2 SoC isn't going to be in the final hardware, just that the Tegra 2 wasn't likely in this prototype device.

This further strengthens my belief that Samsung is looking into another SoC to do the heavy lifting for the new Tab series. If you recall, the first one was the change from a definite 'Tegra 2' to a more vague '1GHz dual-core'.

As always, time will tell.