Inhabitat has a nice story about an upside-down planter that supposedly saves lots of water, not to mention space and generally looks cool. The planter is from Boskke and costs a whopping $75 - $195. Inhabitat claims that this will pay for itself since the system saves lots of water while also being an easy path to green-thumbness (saving cost in water bills and plant costs), I am a little dubious on this claim.
I do think that having upside-down planters are pretty cool, don't get me wrong. However, I don't think that paying $75 - $195 for a smallish planter, hung on the ceiling, is really going to pay for itself, save for in spaces with lots of ambient light. (Plus, I don't think I can pay for the extravigance, based on my graduate student salary.)
I also have to wonder how the plants will grow over time. The site shows basically three types of plants, a Wandering Jew plant, a type of palm, and an orchid. Now, the Wandering Jew plant is a plant that does well in situations where it hangs, since it is a ground-cover type of plant. However, I don't know how palms and orchids would adapt to living upside-down. These are - I believe - plants that grow (generally) "upward", and so my initial thought is that they will eventually try and grow "upward". This is - if my botany memory serves - a growth-movement that is based on gravity. Since the plant is hung upside-down, it will, therefore (if I'm correct), be "forced" by its own growth plan, to grow upward. This will eventually make very interesting shapes of growth, with an orchid who's stem curvs "upward" from the initial "down" position, and palms that splay outward in an attempt to grow eventually "up".
This may mean a growth in the diversity of plant forms that we find "pleasing" (or not). After all, if upside-down fake Christmas trees are "desireable" then upside-down orchids may well likely be, too.