Best Buy is now selling its exclusive white Dell Streak in select stores across the US. It's only available for in-store pickup right now, though it can be reserved and paid for online if you don't want to spend too much time in the store. Boxes containing the white Android tablet appear to still be in transit, as stores that didn't have any on Monday got some yesterday, so keep checking availability at your local Best Buy if you really want one.
Whether the store will eventually lose the exclusivity on the color remains to be seen, but I kind of hope it does because the Streak in white is actually quite lovely in person. It has a smooth silvery-white finish with a touch of shimmer to it and is much nicer than I expected it to be. It may not appeal to everyone, but I think customers would appreciate having more than just black (in the US) or black and red (in other countries) to choose from.
More photos below.