For task management, we are developing a framework that helps with the construction of task interfaces in an easy and configurable way, which can be very useful to create a single application like the one you need. Of course you have to write this applicacion, but it will be much easier for you. You can take a look at it:
It is work in progress and hope it can help, so feel free to check it and ask any questions/suggestions.
I will definitely take a look. However, at this point I'm not actively involved in a BPM related project. The purpose of my post was to ask those more knowledgable than myself whether (1) some sort of "task management framework" is needed and (2) to discover if anyone is working on such a thing, whether conceptual or actual.