In today's New York Times Week in Review, Randy Kennedy discusses the "strange disconnect between the enduring mystique of art theft and the reality of its perpetrators."
Related article from a few days ago at cnn.com: "Everyone wonders, 'Why steal something you can't turn to cash quickly?' Art thieves do a simple risk versus reward evaluation, said Corine Wegener, associate curator of the Minneapolis Institute of Arts. Thieves know that 'even if they receive only a fraction of the work's market value, the cash gained was at low risk of death or injury -- museums can be a relatively soft target,' said Wegener."
UPDATE: Andrew Johnson in the UK Independent covers a lot of the same ground as Kennedy, as does Eric Gibson in the Wall Street Journal (Dr. No makes an appearance in all three pieces). CBC News talks to art theft scholar Noah Charney, who says "this is a classic example of contemporary theft by organized crime syndicates of works of art that will be used most probably for barter or collateral on a closed black market for equivalent value of other illicit goods like drugs or arms." Finally, an article in Slate looks at why it's so easy to steal art in Europe (short answer: "Smaller galleries and no guns").
UPDATE 2: More on Dr. No from Derek Fincham.