I can’t really agree with Jacob Penderworth much at all here – I’ve found Twitter’s web client enhancements heavy on the discovery side, which isn’t high on my priority list. Compare that with what Osfoora for Mac already has – super quick list switching, Instapaper native support, Tweet Marker – it’s already heads and above more useful than the default web experience.
That said, Jacob’s article is interesting. I completely agree that a simple Fluid app could be a solid solution for many, especially for more casual Twitter users.