I think I know what's going on with the PS3.
According to
http://en.wikipedia.org/wiki/Image_Constraint_Token , when the PS3 is unable to create a secure connection between the output device and itself (so no HDCP possible), it reduces it's content to 540p video.
If someone could confirm this by recording something of the PS3 or just try it with some other HDMI-output like a Blu Ray player or a Cable Tv box....