If the Motorola Droid RAZR's 7.1mm frame (at its thinnest point, that is) just isn't thin enough for you, take a look at Fujitsu's latest offering in the Japanese consumer market, the ultra-thin (but not all that attractive) ES IS12F:

The 4-inch device measures a paper-thin 6.7mm, weighs in at a mere 105 grams, and ships with Android 2.3 intact. That's not all this popsicle stick is offering, either; it's also water resistant.