It's actually pretty easy to abuse (in a general sense -- for bibliographic references, or blog pingback (or whatever the hell they call them)) -- you link to a highly scored article, in order to draw more attention to your own article by someone doing a literary search. Some of the citation tracking systems will rank the quality of the link, to use in weighting reverse links. (eg, if someone cited the article 12 times and only cited 10 articles total, that should carry more weight that someone who cites in once along with 80 other articles).

Typically, where I've seen problem is that because people know about the whole 'reference counting' thing, they intentionally cite ALL of their previous articles, no matter how relevant it really is to the current article. When you only get 1-2 articles per year, and publishing affects your income, some folks will do anything to draw more attention to their research.

For perlmonks, though, I personally think that the issue won't be as bad due to the reputation system (we can always -- nodes if people think someone's abusing the system), and I think that the benefits would outweigh the potential risk.