Despite being a PC gamer, I have very little interest in graphical fidelity (I just prefer the games on PC), so I can say that I, personally, see little difference between those PC/360/PS3 shots. What little I do see I don't care about at all. I'm not the perfect test subject for this, however: I think most "casual" gamers -- at least the "casuals" on PS3/360 -- care significantly more about graphics than I do.
I think, instead, that this shows how terribly unoptimized games are for the PC in this day and age. Games are built with the PS3/360 in mind first, and then lazily up-ported to the PC. Obviously modern PCs are perfectly capable of blowing away the PS3/360: it's just that few games care to do show it.
I suppose my objection, if I had one, would be this: I can't imagine how angry and frustrated PS3/360 gamers would be if the overwhelming popularity of the Wii had actually been capitalized upon by third parties, and as a consequence you were playing a lot of games built for the Wii and lazily up-ported to the PS3/360. I remember even the mere mention of such an idea drew enormous derision and scorn. And make no mistake: the difference between the Wii->PS3/360 in raw power is at or near the difference between PS3/360->PC in raw power now.
Look at how the lack of optimization of the PC platform is being defended in here. Let me put this explicitly: some people in here seem to take satisfaction from the lack of disparity between the PS3/360 and PC multiplatform games. This does not mean that the PC isn't more powerful: it means the PC isn't being utilized fully. For a group of people who, almost without exception, care far more about graphics than I do, it is irrational to so vociferously defend inferior graphics. If graphics are a primary concern for you, then you should be begging developers to absolutely blow away anything the PS3/360 are capable of: it's certainly possible, they just aren't doing it because not enough people are begging.
If you aren't asking developers to do this, then your loyalty really lies with Sony/Microsoft (and their respective consoles), not with gaming as a whole, or with the advancement of graphics and technology. And again, there is strong indication that many people in this thread are doing precisely that.