Bono made a surprise appearance last night to sing a couple songs with Irish singer Imelda May during her concert at the O2 (formerly Point Depot) in Dublin. They sang U2's "Desire" and then did a cover of "Christmas (Baby Please Come Home)," the Darlene Love song that U2 also covered in 1987 on the first A Very Special Christmas charity album.
U2.com has some great photos of Bono and May, and there are also a couple short (incomplete) videos on YouTube. This one seems to be the best so far -- it includes most of "Desire." And "Christmas (Baby Please Come Home)" follows below.