What is a Plog? According to Amazon,

Your Amazon.com Plog is a personalized web log that appears on your customer home page. Every person's Plog is different (hence the name) and just like a blog, your Plog is sorted in reverse chronological order.

Essentially, it's postings by authors who've written books I've ordered.
It seems like a good idea, as conceptually I'd like to see what my favorite authors have to say. Sadly, at this point, I have one author in my "plog" and it's by an author I've never read, who wrote a book I sent as a gift.
There also doesn't seem to be an easily labeled way to change authors, either by removing those I don't want to see, or listing those I might want to read postings from.
I like the concept; it's got a while to go before the beta label gets taken off.