Porsche, there is no substitute...for a manual?

Traffic Program (TP) is the radio feature that uses the RDS (RDBS in the US) system which uses FM radio side-band frequency space to identify official traffic update broadcasts. The way the system works is if TP is enabled, then whenever there is an official traffic announcement on a radio station, that radio station would send out a TP marker signal before the traffic announcement, and one at the end of the announcement. The car's audio system would the switch sources automatically so you would hear the traffic announcement and then switch back at the end of the announcement... the driver would need to do nothing.

This works great in Europe, where traffic announcements are of high quality (ie meaningful and usable by drivers) and where alternate routing schemes exist that drivers can actually use to get around issues.

This system, while available in the US, is not supported hardly at all, because of a host of reasons, I would imagine:
Commercial US radio relies on you listening to the commercials around the traffic annoucement in anticipation... so autoswitching would effectively cut out the commercials... and reduce comercial time value near traffic annoucements
Most US highways do not have usefull alternate routing possibilities except what local townies might know about, if they even exist.
The traffic annoucements are usually useless to drivers, as identifying where the incident is relative to where you are, is impossible for a driver to do - incidents are not reported by mile markers on highways frequently but relative to surface streets which is practically useless to drivers without a map and time to study it... not good while driving.
Traffic annoucements in the US tend to come on AM stations, while RDBS is for FM broadcasts.

So unless you are in the US and know you have a local RDBS station that gives you useful data.. .just turn TP off in the US.

Outside of the US and most of western Europe (where the announcements are, of course, in the local language), I cannot say how useful it is.

To compensate, at least the 997.2's have the navigation with xm navtraffic service option... however, it will only reroute you IF you have an active route going. It doesn't see that you are driving along I-55 heading north and suggest alternate routes as you approach an incident, in order to continue going north on I-55. You have to look at the traffic incident messages that show up on the map, click them manually and figure out what to do before you get caught up in a traffic jam. Not ideal.

If we could store customized route requests for drives, that would be great (since we sometimes need to reject streets that don't exist in reality, or want to force a specific route because I know something about the best way to go that the nav system doesn't).. but it isn't possible currently afaik.

More than you wanted to know, I'm sure.