I am 99% sure it is the case… I can, however, say with complete certainty that the Palm Pre can be seen in direct sunlight with the display turned all the way down. The innards of the LCD are reflective, so when a brighter light source (the sun in this case) hits the display, it becomes more vibrant (as implausible as it may sound these days). By the way, this isn’t simply auto-brightness reacting to a bright light source.
A little while back, I took some photos of the Pre (brightness completely down) next to my Rezound (at 40% brightness) outside in direct sunlight compared to how it looks indoors under florescent office lighting with the brightness settings unchanged (keep in mind that the photos, taken with my iPod Touch, don’t really the Pre’s display much justice).
I have some friends w/ the 3GS (or perhaps it’s the 3G?), and while outside, they are actually able to turn the brightness completely down and still see the display just fine (as long as sunlight is hitting it).