So the word "blog" is losing its meaning, eh? I agree. The same thing is happening to the word "podcast."
To me, though, the issue is that marketers are really starting to dive headlong into blogs and podcasts without really knowing what the heck they're doing. That's what results in situations where marketers are calling something a blog that has no interactivity whatsoever but looks blog-like because it has a bunch of press releases posted in reverse chronological order. There are a ton of marketers who think that "podcast" is synonymous with "audio downloaded to an iPod" too.
In attempts to understand blogs and podcasts, marketers will try to force it into a mold they understand - the broadcast model. Thus, unless folks are vigilant, "podcast" will unfortunately become synonymous with "downloaded audio" and things that don't have comments enabled will be erroneously called blogs.