The Nambu Network states that they are 'creating the best possible social messaging experience: elegantly integrated with a superior look and feel'. For me I believe they're well on their way! The app does all sorts of cool stuff and doesn't seem as heavy on your system as compared to tweet deck. They also have an iphone app which will soon be synced with your desktop app. Currently the beta version doesn't support facebook or friendfeed but those will be soon coming.

It has a really nice Mac feel to it and seems to be quite intuitive. Setting up groups is really easy as is searches and displays. Anyway I recommend checking it out. Hope you enjoy it.