Lyle Denniston has the background here, and the stay order here. The obvious question is, does this tell us anything about what the Court might be doing with Baze v. Rees? I think the answer is "no." There are a bunch of reasons for this, but the biggest is a practical one: Even if the Court is likely to rule for Kentucky in the Baze case, denying the application for a stay in this case would leave the lower courts hopelessly confused as to whether executions will be allowed (and in what circumstances) before Baze is handed down. The whole point of taking Baze was to end lower court confusion and settle this issue clearly. So no matter how the initial conference vote went in the case, the sensible course is to stay all executions while the case is still pending.