Agreed, 100%. I saw the screenshot and thought, "Oh, it's Sparrow with some red colors and a new little organization feature. Neat." Sparrow is literally this

Agreed, 100%. I saw the screenshot and thought, "Oh, it's Sparrow with some red colors and a new little organization feature. Neat." Sparrow is literally this exact client design, minus the cute "Actionsteps" or whatever. They could easily add some more color coding to Sparrow and it would fill this need pretty easily (well, that and fix some annoyances, which as is usually the case, is the larger usability problem—simply not being annoying). More importantly, you're right: e-mail is no longer just communication. Our e-mail clients are how we organize incoming tasks and work. This is why GTD and the like focus so strongly on e-mail, because it's become our primary means of incoming information. Organizing that is the problem, and it does need a solution.