We're going to let you flag a user as a spammer or troll when you delete their comments from your journal.
Then, with those aggregate statistics, we'll be able to stop them. (Clarification: after a human staff member reviews it)
We might even do the much-hated/much-loved "Karma" thing, and you can prevent new comments in your journal from people with too low of karma. (people marking them as a troll/spammer lowers their karma...)
We can start discussing what increases and decreases Karma (or "Whuffie", which I'd prefer to call it) in this thread, and whether or not it could work....
DISCLAIMER: We're not actually working on any of this. We're just talking about it right now. We won't make any changes until there's a real problem. We will discuss any real plan before we start working on it.