Most of you have probably read Matt Cutts' answers to his Monday Q and A thread, but I like to document things for the future. I often come to my own site here to search for a phrase that I know I have discussed before, but can't remember much about it. So, here's a few tidbits from Matt's answers.
Big Daddy is fully deployed, and it is a SOFTWARE infrastructure.
The Mozilla Googlebot is the new Big Daddy bot.
The RK value is Live PR, but it has been shut off, never to be seen again by the public. In other words, it will forever show 0. (Note: Matt didn't say exactly this in so many words, it was what he said and DIDN'T say that led me to this conclusion).
New Toolbar PR within the next couple of weeks.
Datacenter 188.8.131.52 is mainly made from newly spidered data. (surmised from Matt's answer)
PR determines crawl depth (old news). Neither age of site, nor submission of a sitemap, guarantees that all pages will be indexed.