The link you provided didn't work so I've included them below. I had to hold my nose to go to the huffington post, but did it just for you. The important things to take from this study so far is that they are concentrating on breast cancer and hoping it may relate to other cancers such as those affecting the brain. However, success in the petri dish and in mice often does not end up resulting in similar gains when it comes to humans. The research work also appears to be concentrating on metastasis which is generally not an issue for primary brain cancers. There is also the highly evasive issue of getting past the blood-brain barrier in humans to deliver the therapy. There wasn't any detail at all related to brain cancers such as GBM so it's difficult to judge just how effective this research will be for brain cancer. However, it is an interesting concept and worth watching. Of particular note, the researcher makes clear that simply lighting up a "bone", a "joint", is not effective and does nothing to stop the cancer. If only it were that simple.
http://www.huffingtonpost.com/2012/09/19/marijuana-and-cance
http://www.ncbi.nlm.nih.gov/pubmed/18025276