I hardly need mention that the justices will be considering five of the six ACA cert petitions at their private conference tomorrow morning (those filed in Thomas More Law Center v. Obama, NFIB v. Sebelius, HHS v. Florida, Florida v. HHS, and Liberty University v. Geithner).
It is conceivable that the Court will issue an order tomorrow afternoon, announcing that it has granted certiorari (and perhaps specifying the questions on which it has granted--if it grants in a case but does not accept all of the questions presented in that petition, or if it wants to re-phrase a question--and even a briefing schedule). More likely, the order will come down at 10:00 a.m. EST on Monday morning.
Of course, it is possible that the Court will do nothing definitive, and re-list the petitions for consideration at its next conference. If this occurs, it would be because the Court could not come to the necessary level of agreement on which petitions to grant, or which specific questions to consider. Given how much time each of them has had to consider these matters, though, I'm guessing a re-list is unlikely.