However, I've been thinking about ways to deal with that, by coming up with a simple liquid deployment and recovery device.
Here's the idea: take a 3oz bottle (the max allowed by the TSA past the checkpoint), and stuff it full of sponge material, so that it extends a bit past the neck. Then soak the sponge to capacity, and squeeze out about 10% of the liquid. This should result in a device that can deploy small amounts of water and also recover it (squeeze until there is a film of water on the neck, touch to water globe, release pressure).
Of course, if water bottles are available after the checkpoint, one could use a larger bottle purchased on site.
Also, after seeing this video, I'm itching to figure out something interesting to do with non-newtonian fluids. The downside here will be what happens when someone sees us dumping cornstarch into a water bottle inside a secure area...
Some good news: the Casio Exilim EX-F1 high-speed camera has been approved for flight. Now the only question is whether there will be enough light to get high-speed footage. Oh well, it can also do HD.