I think someone with deep pockets is trading a tight range, like buying at 13.95 and selling at 14.05. I believe some mtgox customers are currently trading for free temporarily (as compensation for the hack problems) and so they have nothing to lose on that game.
Eventually the market will run out of BTC to be bought or sold at that price and the price will move on.
I think this time it has been going on much longer because of a combination of a reasonable price and deep pocket trader(s) with low cost trades. The stability may also be reinforcing because the longer it goes on, the more folks perceive it as a well balanced price, and as the buy in, it brings in more folks who believe in that price, stabilizing even more, and so on.