In terms of measuring (engine) power, what is a PS? I know what BHP,
HP, and kW is, but not PS. Here's an example of power being measured
in PS:
http://www.dieselmotorcycles.com/models.htm

I'm wondering what it is, and a conversion to horsepower.

Hello tedder-ga

Thank-you for your question.

I have researched this question for you and found the solution.

PS stands for "pferdestärke" which is german for "horse power".

"One measure to be aware of though is the "continental horsepower" or
PS. This stands for "PferdeStarke" - the German translation of "horse
power". In France you sometimes see the same measure being called a
"CV" for Cheval Vapeur. This measure was chosen in Europe as being the
closest thing to a horsepower that could be expressed in nice round
metric units - 75 kilogramme metres per second to be exact. It is
commonly used by car manufacturers nowadays and tends to get used
synonymously with bhp although it is actually a slightly smaller unit
of power. One PS is about 98.6% of one bhp. The conversion table below
covers the units most commonly used to express power and torque."
http://www.pumaracing.co.uk/power1.htm

The above page also provides a conversion table to enable you to
convert from one measure of power to another.  The final link below
contains an online calculator/convertor.

If you require any further information on this subject please ask for
clarification and I will do my best to respond swiftly.

Further information:
http://www.onlineconversion.com/forum/forum_1063529276.htm
http://www.magtrol.com/support/power_calc.htm

prompt and excellent answer!