Space shuttle Discovery landed safely last night (23:14 Melbourne time, 9:14 in the morning in Florida) at the Kennedy Space Center, ending mission STS-121. The mission achieved all its stated objectives, and the shuttle came back in perfect form, despite worries about a leak in a power unit (and the earlier worry about white markings on the heat shields).
It is expected that this will revitalise the shuttle program, with more lauches happening in the next few months. The next planned mission is STS-115, which will again deliver components to the Internacional Space Station. It will be the 19th shuttle flight to dock to the ISS, and it has no launch date set at this moment.
Why are the mission numbers in the wrong order? STS-121 has just landed; the last mission before that was STS-114, and the next is STS-115. Well, mission numbers are assigned when the mission is planned, years in advance. Intervening events can, and often do, change the order in which they are actually executed. A full list of missions, ordered chronologically, can be seen in NASA's Mission Archive (note that, within each year, missions are ordered from last to first).