Amazon just launched their new product, called Echo. It has speakers built in, and I noticed that the woofer was placed above the tweeter.
I do not think I have ever come across speakers that had the woofer above the tweeter. Maybe the small size renders this unimportant.
Are there implications to stacking them this way?
Sound doesn't really care about gravity, so there aren't nevessarily implications. The main problem there could be is vibrations: a low-lying woofer can more easily be held stable in place. But that's probably not much of an issue for the applications this thing is designed for.
The reason they build it like this seem obvious enough: to keep the center of mass low (so the thing won't topple over easily), you want the drivers in the lower half, i.e. the reflex chamber in the upper. The woofer needs to be adjacent to that chamber, thus the tweeter can only go below.
