You may have noticed something like this in my site’s Twitter feed (right sidebar):
It’s there because a spammer used the #birther hash tag. What I do when I see one of those is to click on the time link (“about 2 hours ago” in the sample) and then click the “… More” link on the page that appears. I select “Block or Report” and mark it as spam. I suppose you have to have a Twitter account to do that.
Behaviors that constitute "spamming" on Twitter will continue to evolve.
— Twitter Help Center
Also, I’ve started getting a wave of spam user registrations. As far as I can tell, they are just trying to get me to click on the links of these folks from the registration, because they never actually try to post any messages. Spam is such a royal pain.