Along with the Lean thinking of Kanban goes the minimisation of work in progress, so why are people working on multiple projects at the same time? If tasks from all ‘projects’ are prioritised together, are they really seperate?
If you are getting into wanting things to be together, separate and sorted by when they came into play, when they are needed and how important they are, all at the same time then an automated white-board may not cut it. Intertwingulatrity is noboby’s friend.
Trello’s conceptual model is a list of lists, manually sorted.
[After-thought: can you get at Trello’s data? My Freemind mind-mapping tool stores XML which you could hack to give reports]