Could it be that certain players don't want the price to break 50 just yet? The same thing seemed to be going on when the price almost hit the 32 all-time high.
My theory is that MtGox/CoinLab want to postpone a breakthrough so it can coincide with the launch of their operation in North America. That would look pretty good from a PR perspective.
On the other hand, it might be just a coincidence and I should leave my tinfoil hat at home.
50$ is a psychological barrier. Once we get through, next stop is 60$. But 50$ is a pretty strong number