Pistons react very strangely to nearby redstone blocks. They can be powered by a redstone block even if it should not. This results in extended pistons that are a great distance from the block that is theoretically providing the power. I am not doing a great job explaining, my short video does a better job.

Some demonstrations:
http://www.youtube.com/watch?v=g5hZtUlrlmo

Please fix this, it has made redstone contraptions and logic that use redstone blocks difficult.