Detector Rail

Detector Rails are blocks to be added in 1.5. They are planned to act like pressure plates but will be a type of rail, allowing minecarts to move over them.

When any kind of minecart is on top of the Detector Rail, it will generate a redstone signal. It is not confirmed which blocks receive this redstone signal, but if it acts like a regular pressure plate then the receiving block will be the one underneath the rail, as well as those directly adjacent to it horizontally.