I just tried to tag a new question with a 'googe-charts' tag. The tag appears rendered as the other tags (upon typing a space after the tag chars), but on saving the edit the tag disappears.
I assume there is some attempt at moderating new tags going on, but there is no feedback to that effect. I think it needs something like - 'this is a new tag and will be considered....'
For the record here's the question: