I'm not sure how I feel about the personal tag being automatically generated based on the tag I give a post. It makes sense if I'm posting something with the music tag, or askhubski tag, larger ones like that. But, to use m_w as an example, aaronswartz.m_w as a tag just looks like needless clutter to me. In a case like that it would make me consider using a more general tag that might not as accurately portray the submission for the sake of avoiding that issue.
I agree with all of that. There is little doubt that this will alter people's tagging strategy. It will also significantly alter people's following strategies. Rather than follow #music, and filter users in their entirety based on what you don't like, you may look in #music to find the personal music tags that you want to follow, or filter out only personal music tags you don't, and not the users entirely.
Oh don't get me wrong I'm excited about the potential to further customize who and what I follow (as thenewgreen also brought up), I think my problem right now is more readability related with the way tags are displayed when every post has a personal tag. That's probably just me though.
It was one of the things that we struggled with most, and we tried a number of different options and formats. However, we always kept coming back to this basic presentation. IMO after using it a while, it starts to look natural as your expectation of the functionality adjusts.
In a case like that I would #aaronswartz as the second tag. Think of the increased ability to tailor your experience here. As it was you could "filter" or "follow" a user which meant you took all or none of them. mk is one of my closest friends and he doesn't follow me on Hubski. I don't blame him, I post a TON of content, much of which may not be relevant to him. Now he can follow the aspects of me. Maybe he digs my #history.thenewgreen posts but wants to ignore #music.thenewgreen? It's going to be an interesting experiment. I look forward to your feedback as you kick the tires.