Jerkson is available on play2 development mode from http://takezoe.blogspot.com/2012/08/jerkson-in-play2-development-mode.html

JSON.scala

import play.api.Play._
import play.api.Play.current
import com.codahale.jerkson._

object JSON {

  def stringify(o: Any): String = if (isDev) { new Json{}.generate(o) } else { Json.generate(o) }

  def parse[T](json: String)(implicit m: Manifest[T]): T = try {
    if (isDev) { new Json{}.parse[T](json) } else { Json.parse[T](json)}
  } catch {
    case(e: ParsingException) => throw new JSONParsingException(e)
  }
}

class JSONParsingException(val cause: Exception) extends Exception