http://www.househacker.com/ househacker/tags/glass http://www.househacker.com/permanent/Festive-Lighted-Glass-Block-Howto Switchlite.com explains how the glass works:

The secret of the transformation between clear glass and translucent glass is found in the Liquid Crystal sheet. In their non-energized state, the Liquid Crystal molecules disperse light. When voltage is applied, however, these same molecules arrange themselves in a specific direction in a way that permits parallel light to pass through the glass.

How Stuff Works offers some more detail on the technology involved.

The "Smart Glass", as it's also called, promises to be a huge energy saver for homeowners over the coming years, as it won't be long before smart glass is coupled with home automation systems that turn the transparency on and off at optimal times throughout the year.

There are a few companies on the web that offer liquid crystal privacy glass, but finding a price on any of their sites seems to be impossible, which means that this flick-of-a-switch privacy glass, although very cool, is also likely to be ultra expensive.

Here's another privacy glass gallery from a company that understands the subtle power of lightning bolt bullet points.]]> http://www.househacker.com/permanent/Cool-Liquid-Crystal-Privacy-Glass Glass Block w/ Mini Lights howto. If you're comfortable drilling into glass and haven't had too much egg nog, then you shouldn't have any trouble with this simple project. This is a beautiful craft that emits a warm, soft glow that is really inviting, creating the perfect festive ambiance.]]> http://www.househacker.com/permanent/Make-a-Festive-Lighted-Glass-Block