Wizofoz wrote :"Always thought it odd you could set the park-brake of a 737 in flight- i mean; what could go wrong?"
As far as I can remember on the -200 B737 the park brake was just a latching mechanism and the anti-skid was designed to protect the likely hood of a pilot landing with feet on the brakes, via a spin up channel, the anti skid would not necessarily know if the brakes were foot operated or latched; I am sure this safeguard exists on the more modern versions of the B737 and most airliners.
Outside of a crash landing, I have never heard of two halves of a bolted wheel separating, all the bolts would need to shear and the axle nut go missing; flange failures yes (L1011 Flt 162) and especially in 1950-60's flanged magnesium wheels which were another story.