All tags are triangles now.
Thanks for asking. As I had promised to do the tag rendering and it slipped off my list somehow … . Ok, so here it goes.
You (and all other content managers and admins) will now see little colored triangles “
” at the start and “
” at the end of a tag, both when viewing content and when editing it (in the “Filtered HTML + Tagging” mode only). For example I tagged myself here, or compare Noemi’s post here, which already has tagging applied. The color of the triangles will indicate tag type (topic, action, place etc.) and when hovering over it, you see again the tooltip with the tag name. When you add several tags to the exact same piece of text now, several of these triangles will appear the start and end. So by hovering over each of them, you can see the names of all the tags you applied.
If the colors-and-tooltip combination is not sufficient for visual indication of how you tagged things up, I can adapt that to your wishes easily now, including: (1) colors per tag instead of per tag type, (2) other symbols instead of just triangles, per tag type or tag, (3) image icons instead of the triangle symbols, (4) text color, background etc. of the tagged text itself, though I guess that will make it hard to read and can also lead to weird combinations when tagging text with multiple tags.
@Alberto, you gotta come over here and look at what your ethno-tagging editor prototype has become 
I kinda surprised myself with this solution … it’s still a bit of a hack but it was simple and … umh … simple is beautiful in this case. You can see how it is done in this CSS file. (If you want to adapt the CSS, remember to flush Drupal’s caches after saving the CSS or you won’t see any effects.)