At least N73 should have mechanical shutter. Shutter here (as for N900) means electronic one. Rolling shutter = data is read out line by line, whereas global shutter flushes whole image at once (in very short descriptions),.Most CMOS sensors have rolling shutter, especially the larger format ones. CCD almost always implements global. This is f.e. important for video surveillance w/ biomteric recognition scenarios and moving subjects (what, surprisingly, is one of the use cases that my job is related to)

EDIt: quite late to the party, your post was already answered by patlak and Tiago.