Ok, I’m saying underway, Bing indexed the site yesterday (all of it by the looks of things) which is pretty good in terms of response times, although I’m not sure if this was just a scan and we have to wait to appear in indexes / search results. Doesn’t look like Google has started yet.
Graph courtesy of the Discourse Dashboard
Incidentally, that’s around 4,600 topics and 51,000 posts. Looks like it crawls entire topics at a time, which will pull down all posts in the topic thread.