Sony has announced today that with the PlayStation 4, you can record game content over the HDMI.
But Shuhei Yoshida did Tweet later saying
"We announced today that PS4 users will be able to capture their gameplay through HDMI output in the future. We'll update you when ready."
So this means it maybe a post launch thing but in the end this is the one worry everyone had about the PS4, but Sony did put that worry to rest by saying this.