Static pressure is the pressure of a moving fluid.  It arises due to the random motion of the molecules that make up the fluid.  Static pressure is the total pressure minus the dynamic pressure.  

If you want to look at it in terms of a pitot tube in a pipe, the Dynamic pressure = (1/2)*density*velocity^2 (for an incompressible fluid).  The total pressure is the pressure that would occur if the fluid were brough to rest in an reversible adiabatic (isentropic) process (=density*gravity*height of the liquid in the pitot tube as measured from center of inlet to top of liquid in the tube). As stated above, total pressure - dynamic pressure = static pressure.

hope this helps

Jproj

Another way of looking at it is that static pressure is what a gage traveling with the fluid would read.

Pat  http://www.aquasite.com/skonkworks

Yet another way to look at it (Correct me if I'm wrong.)

Total pressure (dynamic plus static) is read by a pitot tube pointing into the flow.

Static pressure is read by a pressure tap whose opening is perpendicular to the flow (a hole in the side of a pipe wall)

To make something clear here,

Static pressure is EQUAL to Total pressure if there is no velocity.  If you check the air in your tires with a pressure gage, that is the static pressure.

When air is flowing through a pipe , there is both a STATIC component and a DYNAMIC component, as these other gentlemen have described.  Measuring different ways will get you different components of that pressure.  Certain types of pitot tubes are actually used to measure the speed of an airplane since it can eliminate the static component and use the dynamic component to calculate the airspeed.

Just a little more info to help...

Pressure acting perpendicular to the flow is static pressure. we can also say it as the pressure acting on the inner walls of the duct.