The pros of these three methods of technology are that they allow you to get information out in a professional setting. With so many employers looking for technology backgrounds, you can set yourself ahead of other applicants by your use of these sites. You also control the information that goes on these sites. The portfolio to me, is the easiest to control because you do not have to worry about other people posting information on your profile. You can always go back and delete posts that you don't want on there, but that just creates more work for you.
The cons of course is that, depending on your settings, anyone can see your information and post things that could potentially harm your chances of getting or keeping your job. It call comes down to being smart and maybe overly cautious about what information you allow on your professional networking sites. It may be best to keep the party photos to the facebooks and twitters.
Peace, Love and Go Bonas!