The two biggest items being tested right now are the New User Journey and Apprenticeship System. The former introduces new players to the game much more effectively and efficiently, funneling them into the same starting area (Chaos vs. Empire), auto-adding them to a starter guild, and much more. The latter allows highly ranked players to drop their level (stats and abilities capped formulaically) and lowly ranked players to raise their level in order to play together.
As for RvR, fortresses are being removed from the zone capture system, which should result in more frequent city sieges. Whether this is a good or bad thing is yet to be determined because depending on your timing you may not be able to join your friends due to the current instance mechanic. Keep warfare will now benefit from a new difficulty mechanic as well, which grants more rewards when more combatants are present.
Check out the full 1.3.2 patch notes for all the gory details!