It just seems to list it "Motionflow XR240"," which in NA Sony speak would indicate that it's actually 120Hz.
Using google translate I can't seem to find any indication that it's a 240Hz NATIVE refresh rate panel. In the motion section, it states:
"Technology to make 120 frames by generating a new image of one frame between the frame and the frame of the video of 60 frames
per second in the "double-speed drive panel"
The only time I find 240 mentioned is in reference to it's Motionflow XR rating:
"It is equipped with a new backlight on / off technology to double-speed drive panel.
Through the video equivalent to 4x (1 second frame 240)"
which would actually point to it being native 120Hz + 120Hz equivalent backlight scanning, arriving at 240 Motionflow (not technically 240Hz). If this same information can be applied to the US-spec model, then the information provided seems to more clearly bear out that the X900A is indeed 120Hz. On the .jp Sony "Key Specifications" page, it lists "Speed Function" as "Double-Speed Drive/ Motionflow XR240":
Curiously, on the .jp spec page for the W900A, it indicates a panel frequency of "4x drive panel/XR960."
So, to repeat: for whatever reason, in Japan at least, the X900 (X9200) seems to utilize a lower native refresh than the W900. Retailer pages in the US seem to lend this notion some credence. Seems odd to me, but hopefully we'll have a concrete answer sooner rather than later.