This may not be the case with the final retail version of the US-bound Dell Streak, but the units that were given out for beta testing in Texas have duller, more yellowish screens than the ones currently being sold in the UK. That's how it is on my two Streaks, anyway.
The photos in this post show the two devices with their screens set at maximum brightness. The one with the brighter, whiter screen is always the UK Streak.
Again, just because the pre-production unit has a screen like this doesn't mean that the production units will, but I'll hold on to the UK version until I get the official US version to make sure.