There’s been a little bit of talk about it, and I too believe that a pagerank update is on it’s way. Depending on the day, this site varies between a 5 and a 6 on the future pagerank tools. In the last few days, a fourth datacenter is reporting down, which seems to indicate that they are beginning to ramp up for the update. Hopefully the little bit of preparation I did will help with my pagerank here and on my other sites. Mostly, I just did link building, but there’s a bit of SEO going on in the backgrounds as well.
Since I don’t work for Google, I can’t say exactly the procedure for it, but I’m guessing that they take a couple of the datacenters down at a time, update the code, test them and then do a quick update on all of the rest of the datacenters before bringing them all online with the new code. At least that’s how I would do it. Having never worked at a large datacenter, I could be completely wrong. Maybe Matt Cutts will enlighten us.