ergophobe - 8:47 am on Nov 19, 2010 (gmt 0)
Yes, this is theme dependent. The post title should be H1 on the post page and either H1 or H2 on the listing pages. In my opinion, the site name should never be Hanything, but should get wrapped in a div.
This is usually pretty easy to change in most themes and I usually do, more because it offends my OCD personality than for any particular SEO benefit.