This post is for all that Googles for this problem with PS3.
Replacing my AppleTV2 with a PS3 gave me a surprise, connecting the PS3 to the existing HDMI cable used for the AppleTV2 gave me the flickering issue.
The PS3 was actually a 320GB version used in the house for a year on several TV without issues.
Now, on my Sony KDL-60LX900, flickering was regular, in irregular intervals. I tried several tricks settings on the PS3 to fix the problem, like fixed resolution (opposite to automatic), no HDMI control etc - nothing working. Between the PS3 is a Marantz SR5006 reciever, that I suspected as the source of the issue.
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To make it short, as several Google's searchs reported, the HDMI cable was the troublemaker it seems - this was the cable that worked flawlessly on the AppleTV2... This was "proven" with a new cable directly between the PS3 and the TV.
Next, replacing the HDMI cable between the PS3 and my Marantz SR5006 has solved the issue (for now, anyway ... )