I tried the new multifarms for peat and was terribly disappointed. So, I wrote a CC turtle program. 1 turtle can maintain up to a 20x20 peat farm. Minus the water blocks, that's 20x20 - (4x4) = 384 bog earth / peat blocks, which is slightly more than 2 max-sized Forestry Multifarms.
Here's the program if you're interested:
http://pastebin.com/9DgtXEF5
ex:
pastebin get 9DgtXEF5 peat
peat 20 20
The first time, and only the first time, you will need to supply it with some starter fuel. A stack of charcoal should be more than enough:
# drop 1 stack of charcoal into inventory
refuel all
After that, it will snack on peat as necessary to maintain energy.
The only thing you'll need to supply it with is Bog Earth in an inventory (chest, barrel, etc.,.) above the turtle's starting position. I recommend an MFR liquicrafter, TE Cyclic Assember, or equivalent to make the Bog Earth from dirt, sand, and water and a hopper or similar to put it into the inventory above the turtle.
I intentionally did not loop the program. I wanted to force myself to manually kick it off - a price to pay, if you will, for the peat farm. However, please feel free to wrap the main part of the program in a loop that sleeps for an hour or so to allow the bog earth to mature into peat.