I still think the biggest feature missing from tags is something like StackOverflow's "tag wiki".
This is possible for personal tags, but obviously not for public tags. Perhaps, on public tags, since Hubski rejects the idea of moderators (though filtering out a community tag is a rough approximiation - e.g. #spam - I'm not sure how sustainable that is though), top taggers could enter a one-lline description for that tag.
Speaking of tag descriptions, when you tag a new/edited post, you should have a popup with tab-completion and some of the summary. Among other things, this would minimize tpyos.