In that case, then yes, very much so. I will guarantee it is effective if done properly. Proof will be in the pudding in my signature link in the next couple of months.
I think a blog about the company, promoting the company and generally back linking to the ecommerce site would be very effective again if it is updated very regularly, promoted to increase its page rank and it can and should be a very effective tool. Better be!
I don't care about Pagerank and SEO at all. It is about "Branding" and "confidence" to encrease conversion Rates when I buy ads. It is easy to have traffic (you only need to buy ads...) but getting a lot of sales is harder.
it can be good for sriving traffic. host it on your domain, create good content and make sure to have links to the store in every post.