The big pro of news sharing sites is that you are able to stay up-to-date on topics of interest to you. For example, the site that I have chosen, Delicious, allows you to add links - and I believe that when new articles and posts are made to those links, they show up. I am not really sure of this, though. I did a little research and found out they are bookmaking sites. I know that diigo sends an e-mail to everyday with links to things are new on the topics that interest me. This is very handy for selecting resources for use in the classroon and for my PLN.
There seems to be one major con to the news sharing sites - the veracity of the articles. Students tend to believe whatever is on the internet.... and the articles gleaned from those sites need to be vetted for accuracy and bias.