It may have been, and you don’t even know it.  If you’re running an older version of WordPress (the current release is 2.5.1), the odds are pretty good that someone’s been coding behind your back.

About 10 days ago I noticed it on a couple other blogs I have, then I found it on someone else’s blog that I visit pretty often.

How to tell if your blog has been hacked?  You’ll need to view the source code for your site.  You can do this by right clicking the home page of your site and choosing “View Page Source.”  Even if you don’t know code, you’ll be able to spot this - it’ll be about 40 or more consecutive links to pharmacy or gambling sites, usually hidden right in the text of your posts.  a <u style=’display:none’> will preface the links, making then not appear in your browser.  That’s why nobody sees them when they visit your site.

To fix the issue, you’ll need to edit those posts to remove the links, then upgrade your WordPress to the current version.

Here’s more info.