I'm quite new to Seam and it seems that I'm facing the same problem as you describe at the moment :-) Could you find out what you have to do in order to add a library/JAR correctly?
Thanks in advance!
If you're using NetBeans, I find it easier (and more productive) to use seam-gen to generate your projects.
That way, everything is set up for you automatically and you get all of the features that seam-gen provides (build in testing, project skeleton, hot deploy etc.)
@Marco: No, I manually edited build.xml and added directory to list, where I put all neccessary files.
<property name="my-libs.dir" value="d:/jboss4seam/server/default/deploy/my-libs" />
<property name="ejb.dir" value="d:/jboss4seam/server/default/deploy" />
@David: Well, tried that, but couldn't ever see hot deploy... only redeploy :(