I love Plaxo! I have been using Plaxo since the days when it was still in Beta (even Today, their 3rd version is still in beta! but I am talking about days when Plaxo was beta for their first version)! Plaxo has been giving me all that I wanted about my Contacts!! (According to me Plaxo was one of the first implementers of Social Networking.. way before social networking balloon really started blowing!).. As a result of my long relationship with Plaxo, I have almost 1000+ contacts in Plaxo address-book and a few hundred in Pulse. I love to visit Plaxo Pulse website to check what's up with my contacts..
But it would be really great if Plaxo comes up with a desktop application that notifies me for any of my Friend's updates.. Where, I should be able to tell that application, I want 'more' updates for X, and 'less' for Y..
Right now, they have an update RSS feed which I can use to get update about all my contacts.. I subscribe to that feed right now and keep a watch! But I know how often I can reach my RSS reader to read my feeds!! My point is about "Push" mechanism of updates instead of Pull (from user's perspective!!!).
Stay tuned.. 