I'm happy to accept this as the correct explanation, and I'm in no hurry to assign petty motives to Google over this, but in your last link, Matt Cutts says "it can take a few days between when an image appears and when its crawled by the Googlebot." And by "a few days," he appears to literally mean less than a week.
But it's been almost a full month since the WWDC keynote, and nearly two weeks since customers have been posting a barrage of iPhone 4 pictures to the web. So I'm doubtful that Google Images' delayed refresh rate is a sufficient explanation.
Edit: In response to your reply below, you might be right. I've only tried a few searches, but images of major events from the past month seem hard to come by. A search for 'Galaxy S' does give some results from within the past month (the first result was from June 23), as does a search for 'Kindle graphite' (July 2), but presumably refreshes aren't comprehensive. Still, a month-long refresh rate is really surprising. If you need to find images from a recent event, Google Image search may be practically useless.
The more popular results reflect a linking pattern that's from then (mostly linking to the curved Macbook Air style fake iPhone 4), rather than now (linking to the released phone).
Ah right, sounddust's comment framed me into thinking there were no pictures of the iPhone 4 (searchable with the terms 'iPhone 4'), despite previous commenters pointing out they appear after several pages of results. Sorry about that.
But it does mean sounddust's explanation is incorrect, since this isn't a matter of whether 'iPhone 4'-searchable post-WWDC images are indexed. The question is why the images are buried beneath several pages of results.
I can't find any pictures of the World Cup matches, despite it having started on June 11. All I see is stock photography. In fact, I can't find pictures of any event that has occurred in the past month.
Seems like the index is in fact out of date and Matt Cutts is overestimating the indexing speed of Google Images. In the case of the Abu Ghraib photos, it took around 1 month for the images to appear.
But it's been almost a full month since the WWDC keynote, and nearly two weeks since customers have been posting a barrage of iPhone 4 pictures to the web. So I'm doubtful that Google Images' delayed refresh rate is a sufficient explanation.
Edit: In response to your reply below, you might be right. I've only tried a few searches, but images of major events from the past month seem hard to come by. A search for 'Galaxy S' does give some results from within the past month (the first result was from June 23), as does a search for 'Kindle graphite' (July 2), but presumably refreshes aren't comprehensive. Still, a month-long refresh rate is really surprising. If you need to find images from a recent event, Google Image search may be practically useless.