For a long time I have Serbian version of the blog with Google PR 5. This blog is accessible through address draganvaragic.com/weblog. In addition, I did the sub-domain redirection to Serbian blog at blog.draganaragic.com (also PR 5). When I created blog in English, I put permanent URL to blog.draganvaragic.com. The PR of the sub-domain is the same, although the PR of the new blog is 0, of course.
I hope that the explained phenomena will influence better position of the new blog, before the permanent PR change from Google 🙂