got it, I didn't know #tagname already worked.

to be fair I think these tags thing is kind of a failed initiative. twitter for example doesn't treat the tags differently from any words, you can search for words, tags, it's all the same. the only difference is that you can click.

also the fact that anyone can add any tag they want makes it so it is impossible to filter for content using tags since that will be polluted by random or spam stuff anyway.