Because of the upheaval at Freenode, I've migrated to Libera Chat along with a bunch of other Lisp programmers. We have used that as a chance to make some small changes to the channel structure:

• #commonlisp is the on-topic Common Lisp channel (formerly #lisp),
• #lisp is the somewhat on-topic discussion about all Lisp dialects (formerly ##lisp),
• the rest of the channel names should work the same.

The first two lines of the above were mentioned because #lisp on Freenode used to have a non-trivial volume of people asking questions about Scheme or Emacs Lisp due to the too-generic channel name. Naming the Common Lisp channel #commonlisp resolves this issue, at the cost of sacrificing a lucrative and attractive five-character channel name.