The only DM involvement needed in treasure splitting is calling for initiative rolls when combat breaks out. Only by player deaths at each other 's hands will the players understand the importance of making agreements about treasure division before going on adventures together.
Heh. I agree in principle, it shouldn't be the DM's business. However I do see a problem with the recent tendency to "let's give everything to the nominated Party Treasurer" approach - rather than fight for loot, the players all passively let a single PC accumulate all the loot, with the theoretical justification that it will be distributed fairly later.
IME, this NEVER* happens. The only time I saw the treasurer system work was the one time I was a player and the group made me treasurer for a bit, I used the money to min-max item purchases and made sure everyone got +1 stuff ASAP. This soon stopped as the other players reckoned that a Rogue PC should not be Treasurer, so they gave the role to the Cleric.
What NORMALLY happens IME is that the Treasurer is a black hole - loot (money & magic) goes in, it doesn't come out. Either players have an amazing ability to pick the worst person as Treasurer, or most people are like this. You end up with massively under-resourced parties who struggle to survive.
A lesser but related problem is when the lone Treasurer PC is killed, the body & all the loot are lost.
My GM solutions:
(1) Use Inherent Bonuses in 4e.
(2) NPCs give specific amounts of money to specific PCs - "They give you 1000gp each", NOT "They give the party 5000gp"
(3) NPCs give specific magic items to specific PCs, NOT to the party.
*Actually, I think my friend James sometimes redistributes. Normally though IME the Treasurer role is given to the strongest-personality female player in the group. And she never gives stuff out again. I've seen this several times now, with different treasurers.