The video above is a demo on some ideas Mojang has for Minecraft 1.5. The idea is a separate line of redstone that will function as a 'lock' for a repeater, alongside the repeater's line of redstone. All of it will be added after Minecraft 1.4 is done, because this new feature will break many adventure maps, especially ones heavy with redstone. But at the very least, many more redstone devices could be made with this new addition. Jeb also said, "After 1.4 we're going to fix a bunch of redstone-related stuff that will break builds, so that's why we're only using the "safe" version now," in a tweet.
Source: YouTube