On each site in the question lists, the second column from the left gives a visual cue whether the question has been answered (besides the numeric information).  For example, on Stack Overflow, red background means no answers, green background means some answers.  An additional cue indicates whether there is an accepted answer; for example it's yellow on green on Stack Overflow.

The way the same is done on Server Fault is barely readable.

 - Instead of using the background color of the box, the color is only indicated in the thin dotted border.
 - The "accepted answer" cue is apparently a slightly different shade of green, and a green instead of grey number.  This is hardly visible unless you specifically research it.

<img src="http://img695.imageshack.us/img695/1482/serverfaultacceptcolors.png">

Together, this makes Server Fault much less usable than the other sites (for certain usage patterns, of course).