Put the summary of the bug you're having here
What I expected to happen was that when I placed the comparator next to the piston and powered it in a bud position, the piston would update and extend, but they removed that feature.
Nothing happened, which is really disappointing, because that was a great feature.
Steps to Reproduce:
1. Place down a piston
2. Place a redstone power source 2 blocks above the piston
3. Place a redstone comparator next to the piston, and the piston will update whenever you update the redstone source above
Environment
Put your operating system (Windows 7, Windows XP, OSX) and Java version if you know it here
See comments of MC-6077.