There is a link to the left under "my boards" that says "Unblock Bumpies" - you can click this to unblock someone at anytime.
If
you block the original poster of a thread, you'll still see their
subject line because we want to let you know there are replies in there
(it would be weird to block all the replies from you too). But when you
click on the post you won't have to see the blocked member's post(s).
Also, if another member quotes someone on your block list, you'll end
up seeing what they posted. (For anyone who didn't see the earlier
announcement and has no idea what I'm talking about, we've added a block feature).