Well, although that's one step better than blogs that completely lack a link back to the product, I don't find backlinking the actual blog logo to be all that intuitive. Often times I see blog logos that are variants of the actual product logo indicating you're looking at the blog, and so it doesn't make much sense to hide the link there. Just make an explicit link to the product in the sidebar or something. I can't tell you how many times I've closed a product blog page after growing frustrated with not being able to spot a link to the product quickly.
This. I'm always coming across blog posts for products which I DON'T know... and hit hte header link... and it just brings me to the blog home page. Which usually tells me nothing about what the service actually does.