And stunningly, it turns out that the basic technology (texture synthesis) has been around FOR A DECADE. That's right, nerds in the know were running magic in GIMP ten years before Adobe posted their sneak peak at CS5. The upcoming Photoshop with this magic isn't yet available, but the GIMP version is right now (resynthesizer and heal selection), so I thought I'd run it through its paces. I couldn't find the original hi-res photos anywhere (0 results on TinEye), so I had to make-due with screencaps from the original video.
(rollover for originals)
In the first picture, everything except the sky was an easy Heal Selection. The sky didn't turn out right, and I ended up using clone-stamp to cover up the weirdness, and then Heal Selection over that.
For the desert, again I had to clone-stamp part of the scrub-brush over the road first, and then Heal Selection over that.
Finally, for the panorama (which was actually the first image I tried), I didn't use anything except Heal Selection, BUT I had to do the picture in steps (first one corner, then the next, etc).
So what did I find? Well, although the Resynthesizer tool 'works', it's not nearly as easy to use as what is shown in the CS5 preview video. And some of the results were a little wonky. But it's fairly quick and easy, and the output will usually pass a quick glance (but not intense scrutiny).
What you'd need to do this yourself:
Updated Resynthesizer (compiled for windows, sorry)
The patched Heal Selection script
Another guy Resynthesizing the photos
Another guy testing it out last October
Other handy GIMP tips/tools:
Tweaking GIMP to replace Photoshop (sorta)
The Liquid Rescale plugin
The do-everything G'MIC plugin, although its predecessor GREYCstoration has better examples
The FX Foundry is a good collection of scripts
(Gimp Guru used to have good tutorials, but then they switched to WordPress and lost all the graphics)