Safari 5's new "Reader" feature makes my site less readable by justifying the text. Flush-left text (aka ragged-right) is demonstrably more readable, especially when the rendering engine doesn't know how to hyphenate. You never, ever justify text without hyphenation.
Justified text was invented to define columns of text in multi-column layouts (like newspapers). Why they chose to justify the text in a 1-coumn view that's supposed to be more readable is beyond me.