I read many of the useful answers to questions on this site like:
I'm wondering if for a small business who develops websites, and wants to start a blog for the business itself, is it better to use Twitter or a real blog? Don't take in consideration the effort, we know putting up a blog can be a a bit longer, but let's say we use some of the free blog sites on the web.
We are mainly thinking of the blog as a way:
As Rahul pointed out, you should have both because they serve different purposes.
With that said, the purpose of the company blog shouldn't be to write about company news. If that's all you use your company blog for it's a waste of time because nobody will read it. In that case, just use Twitter.
Effective company blogs rarely talk about company news and products. Instead they focus on providing the reader information that will help them out. For example, if your company sells a web security product, use your blog to educate people on how to browse more securely, inform them of new phishing scams, etc. But don't blog about your newest product and how awesome it is. That information belongs on your company's website, not the blog.
So to answer your question: it depends.
Although I wouldn't suggest using Twitter for just company news either. Regardless of the medium, you should always aim for a two way relationship where both parties are gaining something.
I think how you use the terms have changed over the years, so it's really up to you.
Pre Web 2.0 days:
News - press releases and news articles that reference the company
Blog - personal messages from the chief that focused on relevant info targeted to the market that the company was in.
RSS - one feed for each.
In addition to the above, I see successful implementations using this format.
News - frontpage information that can be gathered from multiple subcategories
blog - additional details about product launches, parts 1-X series on explaining how a new product is innovative, etc.
twitter - product releases, industry banter, event announcements.
RSS - stream incorporating all three.
A relevant example off the top of my head: http://rockettheme.com Creating a Blog as I described in Pre Web 2.0 days is one hell of a lot of work. The later day "blogs" are simpler and more a configuration / filtering process of all the content created - typically within a Content management system.
Today, I would Mix and match to suit your model. If your business model values press releases and that ilk, go with a news section in the traditional sense. Not every company homepage needs a stream of new posts to get its point across.
You should have both as they serve different purpose.
In addition, I would also recommend to build company presence on Facebook vi facebook fan page.