I have seen many type of viruses infecting wordpress blogs. You can check if your wordpress is infected by Right Clicking your blog homepage and select View Source. Start looking for the following types of code.
<iframe src="http://virus-site" width="320" height="240"></iframe>
Usualy inserted at the end of your source code, after you close the html tag </html>
Search the source code for <iframe, in most cases your theme won’t have any IFRAME except the virus.