Pawns with shared passions will exchange their knowledge.
Pawns will often chat about skills they both are passionate in.
The less skilled pawn will then gain experience in that field.
If the difference is high they will chat more often and will gain more xp by chatting about that skill.
Also pawns that have shared passions and chat about them will like each other more.
Xp gain respects the daily XP limit in regard that xp gain is reduced if the pawn aquired the points themselves regulary.
You can run this mod with an existing savegame. Removing might give problems though.
Update: Mod is compatible with 0.19 and 1.0 since nothing has changed with the mechanics this mod uses.