Is PR-1 for a two year old website not low enough? I don't know when was the last update, but Google just dropped one of my website's rank from PR-1 to PR-0. I think I didn't violate any of their guidelines. Well, I haven't updated it since months ago. But it's a website and not a blog, mind you.

Apparently, PR1 is not low enough for Google

I'm pretty sure the last update was at the end of June. Not many people I've spoken to had any change though.

It seems the only changes that were made were decreases in PR.

I haven't came across anyone yet that said theirs increased.

I've noticed a massive change in who Google claims is linking to me in Webmaster Tools - it was kind of astounding, actually, because some of those links had been there for years and they just found them.

Luckily, there were more, but I do wonder what they changed that seemed to cause such a massive swing.

I noticed that too. Seems something is working a little more accurately now.

Instead of thinking about the PR of your domain, attempt to examine its ranking in the course of time and if you notice some improvements, you are a winner even if the PageRank of your site is too low to notice. Do not forget that not all forms of link building may lead to higher PR scores.