Ficedula has released V0.02 of an IRC client for the Nintendo DS. As you can see the program is still in the early stages of development:

Things that work:
-Connects via DS WFC preferences (only…)
-Connect to specified server
-Join/part channels
-Send messages to channels (kind of required…)
-Change nick
-Track users in channels (joins, parts, nick changes, …)
-CTCP ACTIONs (/me)
-Quit (…)
-Onscreen keyboard for entry

Things that probably don’t work:
-Privmsg to other users: you may be able to reply but they have to initiate the conversation

According to the release page, nothing else works, but its amazing what the homebrew scene is churning out for these handhelds.