Ok now this happened to me today as well.

I've read a few other threads within the last two weeks when googling other sites so apparently this is becoming a common problem. I am using HDMI for a few months now on the PS3. Finished watching some regular TV, switch to my HDMI input on my tv to pull up my PS3 and nothing... just a blank black picture. I dug out my component cables and did a video settings reboot, it works fine in 1080p on those. I switch back to HDMI, do another video settings reboot, HDMI again has no picture. I figured the HDMI cable maybe went bad but when I connected it to my laptop and tv... it worked fine.

Since IPTV is pretty much MS's take of turning your 360 into a cable box, they should include basic channel service with your gold membership.