There are a number of new ships and rules being used in Praesidius Sector. Some of these rules will be published in White Dwarf and become official, others are unofficial creations by Andy Chambers and various gamers.
Appendix Orkicus (Ork Roks and Hulks)
You can choose whether or not to use these in your games, but remember to ask your opponent's permission when using the Orbital Space Stations and Eldar Void Stalker.