They should have done this five years ago - the old nimble Google of 2001 would have quickly indexed Twitter and Facebook, and every other silo of information. It's only Big Corporate Google that can't acknowledge another source of information for some sort of ego-bruising related reason. "Index all the world's information ... except if it's hosted by a company run by that guy down the street who drives that ridiculous 918 Spyder".
Twitter messages used to appear in Google's real-time search, but after Twitter chose not to renew their agreement in 2011, Google started to follow Twitter's rel=nofollow instructions.
So it's more like the guy down the street who drives that Spyder told Google to go take a hike and they complied.
source 1, source 2