tl;dr OP_CHECKLOCKTIMEVERIFY (OP_CLTV) is the latest function in Bitcoin. It allows people to lock their money until a specified time. It enables many interesting use cases that were not possible / not safe, such as Lightning Network, trustless cross chain exchange (e.g. BTC <-> LTC) and micropayment channels. It is the most exciting new function added to Bitcoin Protocol since Satoshi created it in 2009.
Since the code allows people to freeze their money until a specified time, some people call it OP_HODL. For example, if you want to make sure you will hodl your coins until 2017, no matter it will go to $0 or $1million, only BIP65 would allow you to do it safely (without the need to delete your private keys)
What could you do?
1. If you are pool operator or solo miner: Upgrade to Bitcoin Core 0.10.4 or 0.11.2
2. If you are mining for a pool: Please urge your pool operator to upgrade. Please switch to BIP65 supporting pools, including (as of 2015-11-30):
BiscusFish / F2Pool:
https://www.f2pool.com/BitAffNet:
https://www.bitcoinaffiliatenetwork.com/Solo CKPool:
http://solo.ckpool.org/BitClub Network:
https://bitclubnetwork.com/kano.is:
http://www.kano.is/BW:
https://www.bw.com/KNCMiner:
http://www.kncminer.com/Slush:
https://mining.bitcoin.cz/BTCC:
https://pool.btcc.com/Please let me know if I do not mention your BIP65 supporting pool