Pentax's P-TTL system includes the ability to control flashes remotely, not just as dumb slaves but with coordinated exposure information. There are two required components: a master or control flash and at least one off-camera slave flash. The built-in flash on every K-series Pentax dSLR except the K100D/K100D Super can act as a master/control flash — even on the low-end K-m/K2000. (This is an amazing feature unique to Pentax at the low end. Nikon's i-TTL wireless system is more advanced, but is not available on their low-end cameras or their low-end flashes.)
Pentax's AF200FG is unfortunately not able to act as part of a wireless P-TTL setup, which, in combination with its lack of a tilt head makes it largely useless. If Pentax were to add this feature to a future version, the flash would move from being merely basic to being an entry-level to the whole system and would remain useful as secondary lights for intermediate users.
Both the Pentax AF360FGZ and AF540FGZ can act as both controller and slave units.
The Metz 48 AF-1 can act as a slave, but not as a controller. The 58 AF-1 can do both, but due to a bug in the current firmware, it can't do HSS in master/controller mode. There are currently no known plans for an updated firmware to fix this issue.
The 54MZ-4i can't participate in Pentax's system but with a separate module from Metz can have similar functionality in combination with other Metz flashes in non-P-TTL auto mode — either other 54MZ-4i flashes or more powerful models, or with the 28 CS-2 slave unit (which seems a bit pricey in the US but is interestingly reasonable in Europe).
Sigma's Super version can act as both slave or controller; the ST version can't do either. Be aware that in low light when using a built-in flash as a controller, a EF-530 DG Super slave may be triggered erroneously by the camera's autofocus assist strobe — a problem Pentax and Metz don't share.
The Sigma EF-530 DG Super, the Promaster 7500EDF and the Sakar flash can be used as dumb slaves (simply flashing in response to another flash), but this requires another non-P-TTL flash on-camera, because otherwise they will be triggered before the exposure by the P-TTL preflash. Promaster also makes a slave module for the 5000-series flashes. This has the same limitation.
