I normally think of the term blog as being a web site of dated entries. As a noun, you can have a blog. As a verb you can blog (eg post) something to it.
It would seem there are people out there using the word blog to mean what I would normally call a blog post:
I’m back, starting with an apology for the lack of blogs over the last few months.
Not to single this instance out, because I’ve seen other examples of this use around the place, too. But it just doesn’t sound quite right to me.