For GSOC students, In case anyone was going through the code and finding some difficulty in running stuff, I have updated the kMeans page on the wiki<https://cwiki.apache.org/confluence/display/MAHOUT/k-Means> with a short quickstart shell script that will run it for you. You can tweak the settings and reuse it. Reading the code after running it will hopefully help out in understanding the codebase well.
If any of you have any tips to share, or have made notes of quirks-to-be-aware-of, do post them here for everyone's benefit.
