[R] Decision Trees /Decision Analysis with R?

[stefan.duke at gmail.com]

Hello,

this question is a bit out of the blue.

I am a big R fan and user and in my new job I do some decision
modeling (mostly health economics). For that decision trees are often
used (I guess the most classic example is the investment decision A,
B, and C with different probabilities, what is the expected payoff).
We use a specialized software called TreeAge that some might know.
The basic setup of such simulations is actually very simple and I
guess useful in many fields. So I was wondering whether there is
already a package out there in R that is doing such a thing?

Thanks for any hints!
Best,
Stefan

PS
(By decision tree I don't mean cluster-like analysis of a data set
splitting by identifying decision nods, but the other way around: I
have decision nodes, what is my expected outcome.)