And when Chris Messina, a developer advocate at Google, wanted to introduce two friends over e-mail, he wrote #Introduction in the subject line. No need, he explained, for a long preamble when a quick, to-the-point hashtag would do.

Hashtags, a New Way for Tweets – Cultural Studies –

I’ve been using hashtags in emails over the past year. it started as a way to add a light touch but I like the idea of using it more productively as well.