We have one team working on several projects at once in one Iteration/Sprint. As well as several Product Managers defining the backlog for their Product, prioritized regarding their private issues.
I then only want to create one iteration and put stories from several different projects in it. To do this correctly i would need a product backlog view across all projects which must have kind of a "fine sort" to priorize certain projects or tasks (preferably via drag & drop). This is a must have for every cross-project team.

A workaround would be to have a master project and insert all product todo's into a single backlog. But lacking of a fine grained sort in the backlog also makes this very difficult.