Glass Pane

Glass Panes are a forthcoming block which were announced by Jeb in a tweet. They will be released in 1.8. They can currently be used in-game through the preview release. Their placement behaviour is similar to Redstone, Iron Bars, and Fences. They have the same texture as Glass. They cannot currently be placed horizontally. Glass Panes can be mined and picked up without being broken. (about 1:45 min) Glass panes are present in buildings of villages. When placed without anything on the sides of it it will appear in the shape of an X but when something is placed on the sides of it it will become flat or into a V shape or a T shape depending on the items surrounding it.

The amount of glass to panes is very efficient. Reasons list as:
 * 1) You get the item back when you destroy it.
 * 2) You get more for less.

You can use glass panes under water to build a chamber where you can restore your breath (1 block at head level is enough).

Crafting
Glass Panes can be crafted by placing 6 Glass blocks in a rectangle.

Trivia

 * a 2x2 area made of glass panes can make a hole big enough for the player to fit through, but not rain, water, etc. this can be used as an easy entrance for an underwater house, but not an exit. Iron Bars work similarly.