US PlayStation support has offered up a guide to identify and possibly fix your "blinking blue light" problems (aka Blue Light of Death).
Four fairly general areas of concern are named - TV compatibility, Issues with PS4 power supply, Issues with PS4 hard drive & Issues with other PS4 hardware.
Sony told media last week that the PS4 had a 0.4 percent failure rate (that is of course before clumsy consumers get their hands on the hardware), and even if there are plenty of failure reports online it should be noted that the extent of the problems are unknown.