frame rates for blu-ray format are:
interlaced:
29.97
25
progressive:
24
23.976
50
59.94
the 23/24/25 and 29 frame rates are what most things are done at. the other frame rates for for specially created discs, not normal frame rates
and those games are not maintaining or doing true 1080 HD native.
during post-processing they upscale the image and apply filters to clean up the pixels which can result in having an independant pixel count of 1080, but it is not running that in a pure native mode.
even the 360 has problems. it takes the native input, then applies a hybrid of 4xAA without shrinking it down at pre-processing and then passes that on to the main gpu for the main processing which further adjusts the resolution to maintain frame-rates along with all the image processing, and then during post-processing scales the image to the display resolution.
the PS3 has its image scalar after post processing because when playing a blu-ray movie, it bypasses pre and main, and goes to post processing for image smoothing then to the image scalar which upscales the movie to the display resolution of 1080.
both consoles employ image smoothing in the post-process which developers can use to create fake pixels to give the appearance of higher pixel count with their low texture resolutions employed on the consoles.
to be a native HD resolution, it has to be a HD image going into pre-processing, and stay the same resolution through main and even post, and then the image scalar cant be used.
those sites/articles are all talking about display resolution, not the native resolution.