The portfolio site is nice. It has more of a private feel to it. Plaxo I really like because it pretty much has everything. Such as ways to network, links to all of your favorite sites and even your blog, facebook, and twitter account. Linkedin seemed to me more like a place merely for networking and trying to find employment. I didn't like how you had to make your account public for a certain amount of time in order to create an account. I chose to allow public access for a week. I hope nothing bad happens. I think it is kind of scary having so much personal information flying around over the internet. Who knows what someone could do with a little personal information? I don't know. There are definitely a lot of pros to all of this technology but unfortunately there are also cons that go along with it.
I have invited Prof. Scott Sailor to both my Plaxo and Linkedin accounts.