Slightly better version here: http://www.ox.ac.uk/media/science_blog/brainboosting.html (includes the link to the actual paper and some others at the end).
One of the concerns they raise is that the required equipment is cheap to obtain or assemble yourself which could lead to unqualified people engaging in potentially dangerous self-experimentation. Soo, any LessWrongers willing to give it a try? ;)
Thanks! I changed it to that one.
Article here;
http://www.ox.ac.uk/media/science_blog/brainboosting.html
The article goes on to discuss the ethics of the technique.