I suspect now that Poser 5 was released for free that you will see a reduction in the release of products  that support PP and P4. Lots of people still used P4 and PP because their finances didn't permit them to upgrade, but now that Poser 5 can be had for FREE, there is no excuse to not upgrade their version, other than preference of course.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi