DTW distance measure and K-medioids, Hierarchical clustering

Hello everyone.

I have a couple of questions.

1) Is there an implementation of DTW (Dynamic Time Warping) in Mahout
that could be used as a distance measure for clustering?

2) Why isn't there an implementation of K-mediods in Mahout? I'm
guessing that it could not be implemented efficiently on Hadoop, but I
wanted to check if something like that is possible.

3) Same question, just considering Agglomerative Hierarchical clustering.

Thanks