If you receive an email about Barack Obama having sex with Urkaine women, it is not what it looks like.

According to F-Secure: 

The latest e-mail spam run on the loose contains a link to an supposed pornographic video of Democratic candidate Senator Barack Obama. In order to conceal the trojan's primary intent, a pornographic video will be opened once the file is downloaded and executed. Along with the video named 01.wmv, the trojan drops another malicious file onto the system called 809.exe. Next, it registers the file siemens32.dll as a Browser Helper Object (BHO).

Using US Presidential Election candidate and sex scandal is quite clever move...