You're right!! This is a kind of subtelty worth to remember. You don't have to specify the <body-content> for Classic Tags, however you must specify <body-content> for Simple Tags and it cannot be JSP (the default value is JSP, if you don't type it explicite you get the default value). I wrote about it replying go Jean's post (can be found here)
So Gabriel, either you're wrong or Tomcat 5.x does not fully support JSP 2.0. Just think, how stupid would be of the specs creators be to make the <body-content> mandatory in JSP 2.0. There are plenty of web apps that sonner or later will be ported to containers that support JSP 2.0, and all of the tlds in all of them would have to be changed to explicitly state what content the tags deal with (in pre 2.0 spec the <body-content> was NOT mandatory)
Tomcat is a very friendly container. The XML validation is switched off by default. If You check the http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd xml schema, You can notice, that the body-content is not an optional element. In my opinion if You use <taglib ... version="2.0">, than there is no default value for the classic and simple tags, as the tld file is invalid without a <body-content> element.