Right now there are still seven cases left to announce, including the two most complex and controversial - Obamacare and Arizona Immigration. The only scheduled day for announcing new decisions is Monday, but reporter Philip Klein, who covers the Supreme Court, is hearing that they may add decision days next Wednesday and Thursday. No formal announcement yet.
I don't think they'll announce the two most eagerly anticipated cases on the same day, and probably not on a day with several other cases. Various justices may want to read their opinions and the announcement could take some time. I'm thinking they'll dispose of the lesser cases on Monday, and then handle the other two later in the week, probably on separate days, with Obamacare probably being the final announcement next Thursday.