If the PlayStation 4's (limited) built-in capture functionality isn't enough for you, fear not. Sony announced at their TGS conference that you'll be able to use third-party devices to capture gameplay through the HDMI output, too.
Though be warned, it looks like it won't be available at launch as per tweets from Shuhei Yoshida earlier this morning.
We already got official word from Microsoft that their next-gen console will allow for third-party capture and streaming devices back in early August, so it's nice to finally hear back from Sony on this issue. It's particularly nice for those of you who monetize on YouTube with gameplay videos, and who will no longer have to worry about the PS4's built-in time restrictions with game capture. Worth noting, too, that the PS4 will allow for streaming to both Ustream and Twitch.
We've reached out to Sony for clarification on when this third-party device accessibility will be available, for launch or some time thereafter, and will update this post with any news from them.
UPDATE: It won't be ready for launch, according to PlayStation games boss Shuhei Yoshida: