What I mean is - I have two taxonomies using the same ranges of tags. So I have say two custom posts/taxonomies 'product' and 'article'.
These are both using a tag called 'exercise'.
I want to be able to have a tag cloud with one tag 'exercise' that shows all products and articles tagged 'exercise'. Exactly as it would work if these were not custom posts.
At the moment you can only get duplicated tags in the tag cloud.
I think it would only be possible if there were a change in wordpress to include a 'merged tag template'.
You can get all items with the word 'exercise' by using the search option, but you don't quite get the same posts selected.