The internet is practically an engraved invitation to indulge in gossip and rumor. It's so easy to blurt out whatever thoughts come to mind. Once posted, these thoughts take on the authority of print (particularly if they appear in some book-typeface-like font). Have you ever noticed how much easier it is to question something when it appears in Courier than when it's in Times New Roman? For the poster of the thoughts comes the thrill of instant publication. Only in the aftermath, when untold number have read our blurtings and others have linked to them, not to mention all the comments and comments-on-comments, do we draw back and realize that we may not have acted with either wisdom or kindness.
To make matters worse, we participate in conversations solely in print, without the vocal qualities and body language that give emotional context to the statements. I know a number of people who are generous and sensitive in person, but come off as abrasive and mean-spirited on the 'net. I think the very ease of posting calls for a heightened degree of consideration of our words because misunderstanding is so easy.