It's looking like difficulty will be stable at least through the next change.  The drop in BTC price probably had something to do with that, since it made a whole bunch of miner's unprofitable, and thus were taken off line.  If the BTC price stays around $100 or drops even further, difficulty will likely remain stable or more linear and less exponential, at least until all the unprofitable GPU's go offline and BFL ASIC's start getting turned on en masse.