The proof-of-work difficulty is currently 45.38. (see http://www.alloscomp.com/bitcoin/calculator.php) It's about to increase again in a few hours. It's only been 3-4 days since the last increase, so I expect it will increase by the max of 4 times, or very nearly the max. That would put it at 181.54. The target time between adjustments is 14 days, 14/3.5 days = 4.0 times increase.
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