As its name suggests, the new typeroute~ object lets you route messages/signal dependent on their type. One interesting thing that it does with signals that is different from route and routepass is that it sends out the "signal" message when a signal is disconnected; route and routepass only do this for connections.
While typeroute~ doesn't tell you if the signal is connected or disconnected, by also using route, which only sends "signal" for connections, you can tell the difference, and this can be useful inside of abstractions and subpatchers.
Here are some example patches that show whether an inlet is receiving a signal or not.
PM.Normal~ chooses from two inputs. The left is to the outside world; if nothing is present, it takes its value from its right inlet. I've left this as a general purpose inlet so you can send whatever signal into it, but you could make your own version with a sig~/line~ inside easily enough.
PM.IsSignal~ outputs a 1 if a signal is connected to it, and a 0 if not.
If you come up with a cool modification, please feel free to share in this thread.