If you weren't able to attend MongoSF, you can now view the videos and slides from some of the sessions here. All the videos haven't been uploaded yet so check that link and often over the next week or so to see what's new.
Below is the video from my afternoon session. The morning session went without a hitch so karma fated this one to have technical difficulties (oh well). Enjoy!
Why Spark Will Not Ignite For Me