The Redstone Update is a planned major update labeled as 1.5
Planned Changes for the Redstone Update Note: Most of the changes listed here have no references since most of them were mentioned at MineCon 2012 respectively at the MineCon 2012 livestream (especially the Future Updates with the Minecraft PC Team talk)
More predictable and consistent behaviour
Most of the timings of redstone contraptions will change
Will be more like analog signals
Signal strength will matter (at least for some blocks)
Capacitor block
Only outputs a signal if the input has a specific strength
Configurable like a repeater
Perhaps a revised form of the Allocator
Used to suck up items into a container/transport items between container
Weighted Pressure Plates
Outputs a signal with a strength corresponding to the weight of the entity (e.g. Storage Minecarts) sitting on the pressure plate/detector rail Perhaps a Daylight Detector
Redstone repeater lock improvements[citation needed
Some Redstone bugfixes[1] [2]
Perhaps a new ore for crafting the new redstone machines
May not be available in The Overworld , thus forcing the player to explore other dimensions New ways of transporting items
Using Minecarts similar to RedPower/BuildCraft pipes
New uses for Storage Minecarts
Filling and emptying Storage Minecarts
Specific Rails to empty them
Linking Minecarts together (driven by Furnace Minecarts ) Rendering engine rewrite Current engines has some bugs
Will require a higher OpenGL feature-set
Will include some sort of fallback for older hardware
Support for high resolution texture packs[3] The geometry of individual textures can differ
No support for HD skins
Much faster overall rendering, thus higher FPS.[4] [5]
Includes the lighting fixes first introduced in snapshots 12w39a/b (during 1.4 development)Support for fancy lighting control [6]
Support for more realistic lighting, such as active furnaces only giving off light from their front surface[7] [8] Miscellaneous No new mobs
Perhaps Fireworks for New Year's Eve
Perhaps A method to transfer enchantments from a paper to a weapon
Perhaps One or two ores in the Nether References 