Based on the code used for fancy fade-in and fade out transparency for the dashboard already done above, here how to apply it to plurks on your timeline as well! This however won't apply to the responses, different code will need to be finangled for that.

/*-- Plurk transparency --*/
.plurk_cnt {filter:alpha(opacity=80) !important; opacity:0.8 !important; zoom:1;
-moz-transition:opacity 0.5s ease-out, height 1.5s ease-out;
-webkit-transition:opacity 0.5s ease-out, height 1.5s ease-out;
-o-transition:opacity 0.5s ease-out, height 1.5s ease-out;}

.plurk_cnt:hover {filter:alpha(opacity=100) !important; opacity:1 !important; zoom:1;
-moz-transition:opacity 0.5s ease-in, height 1s ease-in;
-webkit-transition:opacity 0.5s ease-in, height 1s ease-in;
-o-transition:opacity 0.5s ease-in, height 1s ease-in;
}


Again, opacity values can be adjusted to your liking, as can ease-in and ease-out to adjust how fast or slow the fade-in is.