A lot of important development discussion happened in those channels: en.bitcoin.it/wiki/IRC_channels
At www.reddit.com/r/Bitcoin/comments/5pvp6m/is_there_a_log_for_the_bitcoin_irc_channel/ "Is there a log for the bitcoin IRC channel?" Luke Dashjr comments:
No, it is meant to be private without logging allowed.
User "midmagic" (TODO identify) then comments:
The #bitcoin channel on Freenode is "officially unlogged." That means we officially don't publish the logs anywhere, and if we find that logs are published somewhere, we ask that they be taken down
Some IRC logs were dumped into the Bitcoin blockchain at: IRC log dumps where they cannot be deleted.