Now Playing script for Textual that works for both online radio streams and music library.

np.scpt

on textualcmd()
	
	set nowPlaying to "I'm not currently playing anything."
	
	# iTunes
	if isRunning("iTunes") then
		tell application "iTunes"
			if player state is playing then 
				if current stream title is not missing value then
					set nowPlaying to "/me is currently listening to '" & current stream title & "' on " & name of current track & "."
				else
					set nowPlaying to "/me is currently listening to '" & name of current track & "' by " & artist of current track & " from '" & album of current track & "'."
				end if
			end if
		end tell
	end if
	
	return nowPlaying
	
end textualcmd

on isRunning(mediaPlayer)
	tell application "System Events"
		tell application "System Events" to return exists (processes where name is mediaPlayer)
	end tell
end isRunning

Put this file in ~/Library/Application\ Support/Textual\ IRC/Scripts/np.scpt

The Application Support folder path doesn't work any more. As per the wiki, the correct path is...

~/Library/Application Scripts/com.codeux.irc.textual/

Also, the /me is verbally outputted to the channel now, instead of being sent as an action. So I changed it to just "Listening to...".