Twitter does not define any open standards. Actually microblogging is not high tech. On instant messaging Google chose the open Jabber/XMPP standard. Twitter is technological rather uninteresting. The only interesting subject could be the user base. OTOH those who buy Twitter will have to deal with all the old cruft.
Google did buy the wiki provider JotSpot and did not make anything out of it besides a simple web site editor called Google Sites. This has nothing to do with wikis any more. I doubt Google can do much with Twitter – I rather like them to take Laconica and help improve the code and be part of a openmicroblogging network.
Google is so big that it does not make sense to quire external technology. It would be a silly move to aquire Twitter. The times were it makes sense to spend a lot money to buy web companies is over.