Here’s an example of Cairo’s font rendering, as seen in Camino 1.2+ for Mac, via hicksdesign: 

If you take the time to read the comments on the hicksdesign post you link to, you’ll notice that Camino’s rendering was due to a bug. To quote David Smith:

Jon: could you put a note about the bold rendering being due to a Cairo bug (not synthesizing a bold font, specifically)? It seems dishonest to leave it up there as a shining example when it’s actually incorrect. 

If you compare the rendering of Camino 1.5, which as the version number suggests is newer than Camino 1.2+, on Amazon UK to that of the screenshot you posted, you’ll notice that it now renders virtually identically to the Camino 1.0 and Safari 2.0 screenshots. The reason for this? It’s the correct rendering! I agree that the buggy rendering does look nicer, but it’s a result of the inability to synthesize a bold variant of a font when the font has no native bold itself. You could get an identical rendering in Camino 1.0 and Safari 2.0 if you disabled the bold styling on that navigational element.

Spreading misinformation really isn’t cool.