Yers, if you keep the same exact file paths it is not difficult to create a 301 redirect that just switches the old blog domain name for the new subdomain on your company's main website.
The technical details depend on what server you are using, Apache [webmasterworld.com] or Windows IIS [webmasterworld.com] - those links go to our respective forums for those two most common server types.
I would recommend redirecting the blog home page to the company website home page and linking to the blog from the company website home page rather than redirecting the blog home page to an inner directory (or page) on the company site... Redirects from a home page to an inner page are treated differently than home page to home page in my experience.
You should be able to go 'straight across' with everything else, but I've had a 'not so good' experience with redirecting a home page to an inner page on another domain, even though it was the correct way to do it for my visitors.
I want to merge them because it's the company blog, and the content is directly related to the company site. The blog is being used to reinforce the brand. Our audience for both is the same.
We mostly link back to content on our company site, anyway. While we then create links pointing to the company site, we have extremely limited link diversity. If anyone links to the blog, the blog gets the benefit of link diversity, not the company site, which just has links coming from our own blog. It's the company site we're trying to promote most.
In addition, by putting the blog on the company site, we'll bring traffic to the site using a variety of keyword phrases that we wouldn't otherwise use.
Users also seem to think of the blog as its own entity and don't associate it with our company site/brand. The two should blend.
Can anyone let me know what other SEO benefits we could get by keeping them separate?