Actually there will be a new concept in the next EJB3 draft, which will allow you to share some annotations between different entities provided that they share a common superclass and that this superclass is *not* an entity

So basically

public class WidgetBase {
 @Column(name="column")
 public String property1;
}

@Entity
public class MyWidget extends BaseWidget {
 @Id(generate=GeneratorType.AUTO)
 public Integer id;

 @Column(name="column2")
 public String property2;
}

MyWidget will persist id, property1 and property2 in one table. not that WidgetBase is not an entity.
But you won't be able to override @Id if the id property is held by the BaseWidget. Does it solve your problem?