We already knew about the reputation changes from the PTR 5.2 Patch Notes, but let's see what exactly is going on here.

Sunsong Ranch Work Orders
An announcement board, if you can call it that way, was added to the Ranch in the last PTR build. There, you can grab a Work Request daily quest for one of the MoP faction.
The quest will ask you to plant 8 plots, harvest them and send them to the specific faction. That will reward you with some gold and 300 reputation for that faction. I have no idea if the Commendation Tokens will influence that reputation, but I see no reason not to.

In order to take those quests, you need to be Exalted with The Tillers and you'll need all the plots of the farm unlocked.

Basically, you'll be able to use the farm to get 300 reputation for any two MoP factions each day. It is known that The Black Prince wont be on that list, but as far as I could see some other reputations are missing from that list as well.

Dungeons and Scenarios
From 5.2, the first dungeon and the first scenario of the day will reward you with some reputation for the faction you choose when you queue for the dungeon or scenario.

Currently, the reputation for your first heroic is 750 and 325 for your first scenario (source).
The reputation will be rewarded along with the valor points, that means that you'll have to complete the dungeon to benefit from these new reputation bonuses.

Unfortunately this feature does not work in the current PTR build and we don't know which factions we can select. It would be interesting to use this feature to farm some old factions reputation.

New 5.2 Factions and Raiding reputation
The only new introduced faction that will have valor rewards will be the Shado-Pan Assault.
You can get reputation with them from the Throne of Thunder raid instance. You can gain the reputation from LFR as well and beyond a certain threshold, the reputation will be gained only from bosses (source).

Sunreaver Onslaught and Kirin-Tor Offensive factions wont have any valor rewards and the reputation will come from questing, just like any other MoP faction.

Remember that everything can change since these things are on PTR at the moment.

Now tell us, what do you think about 5.2 and its reputation changes? Would you change anything?