Apart from seeing IRC still being mentioned quite often here and in other tech-oriented places, and a bunch of nostalgic feelings, this might be the final thing that is going to get me to pick it up again were I left it like 10 years ago: no idea this existed, but seems really valuable. Linux/Windows client recommendations anyone? Servers?
I favour Hexchat. Freenode is where a lot of the hacking talk happens, but not all; irc.mozilla.net and irc.gnome.org are other possible networks you might want to visit for "serious business". OFTC is another network where e.g. Clang and Debian things happen.