Miners on the Bitcoin network signaled that they would begin enforcing a new set of block acceptance rules concerning the handling of "anyone can spend" transactions, commonly referred to as "Segregated Witness". For users of the actual Bitcoin system and actual Bitcoin software, this news comes with the usual "soft fork" related increase in the risk of chainsplits and orphaned blocks. For users engaging in fringe behavior on the Bitcoin network and seeking to abuse the new "rules" surrounding the "anyone can spend" edge case, there exists incredible potential1 for "your loss".
This move by Bitcoin miners circumvents an effort advanced by assorted social engineers to attempt enforcing this new "anyone can spend" ruleset through a loud tantrum. It remains to be seen how large a pile of coins the brave and the duped are willing to amass under "anyone can spend" conditions in order to tempt miners to abandon this new "soft forked" ruleset.
From Qntra, December 28th, 2015
The chief idiocy in the Blockstream camp is that if miners decide to stop enforcing the "soft" forks that Blockstream needs, the miners are somehow on "invalid" chains. Soft fork enforcement is nothing more than a courtesy extended by miners. Should miners trigger activation of segregated witness, and a super majority of miners later decide to stop enforcing its rule set, Blockstream is out of luck. Luke-Jr's protests about the "valid" blockchain would be as impotent as his protests about the valid Pope. So long as the longest chain that wins verifies on the actual reference Bitcoin client, life goes on.
There are hazards to artificially trying to introduce new levels of trust to a system that doesn't require it. Softforks that explicitly create an incentive for their own revocation create an extraordinary moral hazard