This indicates an attack attempt against a Cross-Site Scripting vulnerability in Wordpress.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application. A remote attacker may be able to exploit this to execute arbitrary script code within the context of the application, via crafted HTTP requests.
Wordpress Version 2.1.1
System Compromise: Remote attackers can execute arbitrary script code on vulnerable systems.
Currently we are unaware of any vendor supplied patch for this issue.