The Nobel Prize in Physics most often recognizes fundamental (and usually rather esoteric) discoveries in the field.  For example, the 1990 prize was awarded for "pioneering investigations concerning deep inelastic scattering of electrons on protons and bound neutrons, which have been of essential importance for the development of the quark model in particle physics."  What made the 2000 prize special was the fact that it directly recognized contributions to technology, specifically, computers and information technology. 

Other Nobel Prizes have, of course, had important practical implications (the invention of the laser, for example), but by giving the 2000 prize to Jack Kilby, the Nobel committee took notice of what may be the most important technological advance of the last 50 years--the monolithic integrated circuit, better known as the microchip.  It also gave the prize not to a physicist, but to an engineer and one who does not hold a Ph.D.  Kilby's invention laid the foundation for the entire field of microelectronics.  According to his TI biography, sales of integrated circuits totaled $115 billion in 1996 and the worldwide market for electronic products incorporating microchips reached nearly $1 trillion in that year.  This market will only continue to grow.