If it has not happened to you yet – it will. I cant say for certain that hackers are indescriminate but it sure seems like it – just opportunists, kinda like spammers – it may be argued that it is a victimless crime, but those of us who make our living creating things that people may actually want to see on the internet do not appreciate their work… I just had to deal with the Pharma hack on a wordpress install and though it took a couple of tries i found that this was the best set of instructions for cleaning it up…
http://www.pearsonified.com/2010/04/wordpress-pharma-hack.php