I actually wrote to Jeep a while back about whether they had any plans for a hybrid Liberty. My wife & I love the LIberty and would love to have one. It fits our lifestlye perfectly and we've both had great experience with Jeeps. In fact, I just sold my '96 Cherokee with 98k miles on it and it was still running great.
Jeep's response to me was they had no plans to introduce a hybrid vehicle.
I have no idea about a diesel hybrid.