In liferay 6.0 you can use
JournalArticleServiceUtil.addArticle
But now there are some new arguments in this method:
long classNameId, long classPK
What does its mean?
For adding journal articles, it looks like you can pass 0 for both values.
It appears it was added for your convince as a 3rd party developer to find articles created for your application quicker. See, http://issues.liferay.com/browse/LPS-16960.