Signs before the release.
Signs are entities that have text on one side of them. They may only be obtained through crafting.
Signs were originally added in Survival Mode, but removed shortly after. They were re-introduced in infdev, where they then had greater use.
After placing the sign, a window pops up asking you to type out the text that will be placed upon the sign. The sign's text may only be changed after removing it and placing it again, upon doing this the same window will appear. As of a the 07/02/10 update (Secret Friday update #3) signs became smaller. You can place signs in the ground sticking out or on walls with out any post grounding them.
Signs may be used to mark property, leave directions, state rules, or even leave out your poetic stylings for travelers to stumble upon. Signs can also be used to create furniture such as the sides of chairs or ends of beds.
When created, signs always face towards the player. They are not stackable.
Signs are currently only available in Alpha.