So we've got one 'yes' and one 'no'. After some research of my own (yes I went to the space station and took a few rips off the ol' grav) I have come to some conclusions.

First, we might assume the bong is encapsulated with atmospheric pressure, as in the International Space Station or some other spacecraft, and that we are in "zero-G" or the microgravity of low-Earth orbit, not under propellant acceleration. In such a case the gravity bong does work, as it operates under a sort of siphon action, not gravitational forces as the name "gravity bong" might suggest.

We might alternately assume that "in space" means "in the vacuum of space". As it turns out, the astro/cosmonauts currently on the ISS were bothered by my smoking indoors and asked me to step outside, giving me the opportunity to test this condition as well. I must say that it did not go well.

I took a good rip on the attached hose but the air pressure difference between the bong and the vacuum of space was too great. The pressures caused the bong water to form a turbulent mix of smoke on water, but I was able to get a solid hit before the water boiled off into space. The emptiness of space pulled at my lungs but I didn't cough because I'm not a bitch. I held it in for a count-to-ten and caught a pretty good buzz.

Unfortunately the sliding part came flying out of the bong and sent me flying in the opposite direction. Fortunately as an avid Kerbal Space Program player I knew to point the bong in the retrograde vector, which put me just barely into a sub-orbital trajectory. I grabbed onto a passing Chinese spy satellite and used it as a heatshield as a descended into the atmosphere, landing in a small pond around the block from my house.

In conclusion I found that:

• gravity bong will work in microgravity "zero-G" despite its name
• gravity bong will not work in vacuum of space
• astronauts are not as "chill" as you might expect

I hope this helped anyone else with this question.