Recently we have started working with Intel's TBB and found that when debugging containers we cannot really watch the elements and their data.
Is there a flag setting, a plugin or a tricky way to enable this? (maybe a script snipit for Visual to work with)
What you are looking for is a expression evaluator. You can't do this with a simple flag, as there are an infinite number of data structures. But an expression evaluator is indeed a kind of plugin, it's definitely code.
I'm not answering your question "is there one" since I don't know, but instead of using an expression evaluator I'd use a custom visualizer. They're a pain to write but work relatively well afterwards.
The best resource is: http://www.virtualdub.org/blog/pivot/entry.php?id=120
TBB is a relatively new (but exciting) library, and I won't expect extensive tools for debugging right now. You might try to implement a simple ring buffer (http://www.ibm.com/developerworks/aix/library/au-buffer/index.html) for logging and debugging.