What else happens that day? Oh right: "this".
The two maps in question are Arica Harbour and Laguna Presa, Conquest and Rush maps respectively. The update will allow both modes to be playable on both maps.
The move is part of EA's Project Ten Dollar deal on cutting down pre-owned games. If you have a copy of the game pre-owned, you'll have to buy a VIP code from the PS Store, Marketplace and the PC version.
Producer for the title, Karl Magnus Troedsson said the move was "'mapathy' without getting nickel-and-dimed". He did not just go there, girlfriend!