Hibernate version: 3.0.4
Name and version of the database you are using: MySQL 4.1.12

I'm using Tomcat, Struts, Hibernate and MySQL. Is it possible to use Hibernate Annotations 3.0beta1 to generate the mapping files for MySQL? i.e. without using EntityBeans -- Tomcat is only a servlet container, not a full-gledged J2EE-Appserver.

If so, where can I find some code samples?

EJB3 Entity beans are not EJB components, they are plain POJO classes. So what you request work out of the box.

In other words,
<class name="MyClass"> == @Entity public class MyClass { ...}