Did Meryl Streep & Pierce Brosnan sing in public before?

Question

I loved the talented cast of Mama Mia. Did Meryl, Pierce, and Christine Baranski ever sing in a movie before? I can't wait to buy the DVD!

Answer 1

Meryl Streep sings in A Prairie Home Companion as well as Postcards from the Edge.  Christine Baranski sings in Chicago and a little bit with Robin Williams in The Birdcage.

I loved Mamma Mia, too!  :)