There are some PS4s in the wild that are experiencing issues, with some of them just not working at all, but to Sony, this seems like it's no big problem at all, because it represents 0.4% of all PS4s sold so far. Sony has said:
A handful of people have reported issues with their PlayStation 4 systems. This is within our expectations for a new product introduction, and the vast majority of PS4 feedback has been overwhelmingly positive. We are closely monitoring for additional reports, but we think these are isolated incidents and are on track for a great launch.
There have been several problems reported, which leads us to believe there isn't a singular problem that could impact a broader percentage of systems. The number of affected systems represents less than .04% of shipped units to date, which is within our expectations for a new product introduction.