take a look at the remail website! this interesting project by ibm research comes close to my vision of an ideal “communication center client” :) remail is flow-based instead of just entity-based, integrates different kinds of communication facilities and information sources (i guess it’s modular and easily extendable), ties information to time/calendar functions and offers more flexibility and better customization (e.g. various message flags, better categorization, keeping track of important things etc.).
let’s hope there will soon be a public (open source?) prototype to test-drive..