I'm sure it is indexing pages of this forum every second of every day. Google is indexing my forum every second of everyday and this forum is 10 times bigger than mine.
Well, you can find this thread in there - http://www.google.co.uk/search?num=...+does+Google+index+this+forum+(DP)+??&spell=1 - that's in around 45 minutes
DP forums has been indexed from Googlebots frequently, ranged from 15 - 35 minutes each. I have no scientific number backing up what I said but it is from my own observation.
Depends on many factors and no, being big doesn't mean you are indexed quickly! I've got a site which indexes every single post of mine in 40 seconds - 2 minutes, yeah and most of my posts end up in TOP 10 in Google
Google indexing is base on your on-page optimization. If your webpage fully static with meta title and description then google automatically crwale your webpage. The content on your site and webpage format also matter while indexing. So before starting any promotional work be aware that you are ready with all of the basic aspect which google recognize.
Google Love DP much.. and i hope they have a New Bot For DP lolz It sends its bots and index the pages every few minutes. Well, We can adjust that in the Webmaster Settings Too ..! Dont know whether Shawn(Our Dear Admin ) Had Done any Changes there