I truly believe Diana is the first AP Jungler that can replace the current top jungling picks (Fiddlesticks has no way to close the gap between his target, stick to him/her, and is extremely reliant on blue buff).
With her arrival, I wanted to know how viable this team comp would be:
Top - AD Carry with moderate sustain (through lifesteal or abilities) and a good escape mechanism - AD Nidalee would be a good choice, IMO, thanks to her traps which can prevent most ganks and healing with her E. Vayne would also be viable thanks to Tumble, and Kayle should also be pretty good.
Mid - Aggresive ex-top laners capable of closing the gap between their target and deal heavy damage in a short amount of time, zoning their opponent and crippling their late game - Some excellent choices would be Renekton, Darius or Jax.
Bot - 2 tanks with heavy sustain and tons of combined CC - This is the really innovative part. Having 2 people able to turret dive and resist a lot of damage means you can effectively push the lane, dive the enemy's ADC and let the jungler do the damage.
AP Carry Jungler - Here's where Diana comes in. With all the CC and diving potential from bot, she should be able to quickly take out her objective without any fear of the enemy's tower. Since AP Carries scale better with levels than farm (and a good jungler will always try to stay on the same level as their mid/top partners), Diana should not have much problems with the inferior farm available in the jungle.