The diplomacy options have been upgraded and alliances now come in two new levels instead of just one. Share Intel and Full Alliance. The new alliance settings allow you to share a lot more information about your empire and your scanned enemies with your alliance partners.
All existing alliances have been converted to Share Intel alliances. In a share intel alliance the players share information about their own ship locations, their own planet locations and any enemy planet, ship or minefield information which has been learned.
Full alliance agreements also share detailed information about each of your planets including your starbase information and resources on the planet. It also shares detailed cargo information about your ships.
Only full alliance alliances will be broadcast to other players when attempting to achieve the victory conditions Planet based win condition games.
Both Share Intel and Full Alliance settings are considered alliances, however, so the Max Allies setting for the game applies to the Share Intel alliance level.
You should all start seeing a lot more info from your allies as host runs on your games this week.
Special Note: Because of the way data was formerly stored, there is a possibility you will see some minefields which you know do not exist (but your ally thinks they do) it will take a couple of turns for this information to correct itself and then it will not happen in the future.