It looks like Google used the new year’s eve to update the nominal PageRank around the web. My established websites didn’t experience any fluctuation, but I noticed that many of my recently created niche websites gained PageRank.
Most of them went from PR0 to PR2. I was surprised to see one of them jumping from PR0 to PR4 though, especially because the site is less than six months old.
What about you, did you notice any changes?
Finally, it looks like the frequency of the updates is indeed increasing. The last one was just two months ago (late in October), so keep an eye for the next one around March.