While we're working to support a wider range of locales in our hashtags, we're considering whether or not we allow punctuation to appear within a hashtag.
For a long time, we've supported and used hashtags along the lines of #v1.4 and #bug-ticket on our own instance, but we're considering removing support for those to make searching more consistent across different database backends and possibly to become more consistent with Twitter's hashtags which only allows underscores and not periods/dashes.
We'd love any feedback we can get from members of the community on this, particularly if anyone else's organization uses periods and dashes in hashtags and would be bothered by seeing them go.