One area I think may be interesting to experiment in is hash tagging. I think this addresses many of the concerns @codinghorror has and has been mentioned before quite a few times. One issue though is that # is already reserved for tags and categories so it would have to be a different symbol (or a double #) .
Tags are now per topic, there is no clean way of tagging a post. But … let’s imagine for a second that this exists.
Tales from Sam’s desktop
Here are the awesome tales from Sam’s desktop
More of the story##sams-desktop-adventures
Then users could watch ##sams-desktop-adventures and be notified of all new posts with that tag.
The ##sams-desktop-adventures would automatically become a link, clicking it would give you search results for all posts containing the hashtag.
This to me seems far more in the spirit of solving the specific issue without needing to revert to the “stalking” aspect of user following.
Not saying this is happening right now, but I think we would be far more open to having a system like this (default off) for communities that want “post tagging” vs “topic tagging” ability.