It would be nice if this could be bundled in the dev-java/icedtea6-bin package as well. Common use is in the Apache Ant build scripts.
icedtea6-bin is mainly meant for easier bootstrapping of source-based icedtea, so we don't aim to make it feature complete. Is there a reason you can't use the source-based icedtea?
The main reason I went for icedtea6-bin in the beginning was due to icedtea package being testing for my arch (and for what matters, for all arches).
I've switched to using the icedtea package now, but I still think it would be a nice feature since by emerging the icedtea6-bin you don't have to pull in a lot of other packages required for building the icedtea package.
Adding a small elog message to the current icedtea6-bin ebuilds might be useful, though (i.e. let people know that icedtea6-bin is built with a limited set of features and direct them to icedtea for more features).