Users clearly want the abilty to ignore every entry and comment from a given user, even in communities. It seems that people are now resorting to doing this in S2 layouts, which is clearly the wrong place to address this. It seems to me that implementing this kind of thing shouldn't be too hard. The main problem is that it's hard to filter out items without reducing the number of items present due to the way the data fetching works, unless the filtering goes in right in the guts of the API, which I think is the wrong place to put it.
I'm a bit rusty on this stuff since I've not been doing much other than S2 for a while now, but I'm thinking perhaps a couple of new API functions which can be called at some point in the data-fetching process to filter out entries and comments respectively. Depending on where in the proceedings this is done, I expect that the input to the former would be a list of entries and the latter would be a tree of comments.
There's a Zilla bug filed about this already, but if there's any discussion to be had then let's have it here since Bugzilla sucks for discussion.