In DWM Issue 430, Steven Moffat revealed that the production team and him have decided to change the order of the announced episodes in Series Six. Originally the episodes were set to be as planned - 
Episode 1 And 2 - Opening Two Parter by Steven Moffat
Episode 3 - 'House Of Nothing' By Neil Gaiman
Episode 4 - 'What Little Boys Are Made Of' By Mark Gatiss
Episode 5 and 6 - Two parter by Matthew Graham
Episode 7 - Mid-Series Finale by Steven Moffat

But now the episode by Mark Gatiss has been moved to the second part of the series, which has denied rumours that Amy Pond will die in the mid-series cliff-hanger, as Karen Gillan is in this episode. As of Now this is how the episodes WILL be set - 
Episode 1 And 2 - Two Parter by Steven Moffat
Episode 3 Unknown Episode by Steve Thompson
Episode 4 - 'House Of Nothing' by Neil Gaiman
Episode 5 and 6 - Two Part Story by Matthew Graham
Episode 7 - Mid-Series final by Steven Moffat

SECOND HALF OF SERIES

Episode 1 - Series Opener by Steven Moffat
Episode 2 - What Little Boys Are Made Of by Mark Gatiss
Episode 3 And 4 Unknown Stories 
Episode 5 and 6, Two Part final by Steven Moffatt

More Information as it becomes available