I have found the lyrics to An Dreoilín but have not found a recording. The lyrics in Irish and English can be found here: The Wren Song ( An Dreoilín ).wmv

I've found recordings in English (such as this:
The Clancy Brothers & The Furey Brothers - The Wren Song ) and Joe Éinniú (Joe Heaney) sings a little of it in Irish here: Dreoilín, An but I haven't found a recording where all or even most of the song is sung in Irish. If anyone knows of such a recording, please let me know.

Not to be confused with this song by The Maimin Cajun Band by the same name (which is quite a fun song but not the one I'm looking for): Maimín Cajun Band, Seán Monaghan - An Dreoilín (+zany slides)