I've just spent some time updating my ancient iPhone 3G to iOS 4 and noticed the preferences icon had changed. On closer examination it looked distinctly dodgy - as if a monkey who had only seen the original for ten seconds was forced to reproduce it from memory. Compare the iOS version shown above to the OSX version shown below.
The clearly defined gear teeth of the original have been replaced by sharp points which are clumsily spaced. The pitch of the smaller cogs' teeth is different from that of the larger one. The lighting is inconsistent - the perforations in the background are lit from above but the large cog is lit from top-left. The cog spokes are thinner and the metallic, brushed steel effect of the original has been completely lost. All in all, a real surprise considering Apple's normal attention to detail with UI graphics.
I can only imagine they knew what they were doing. Perhaps they've infringed someone else's patent and had to redraw it? Or perhaps they've decided to expand their existing patent range to include all depictions of cogs? Who knows - all I know is it's ugly and it annoys me.