Per IMDB, these musicals are in production or pre-production:
Follies (2009)
Jekyll & Hyde (2009)
Sunset Boulveard (2009)
The Princess and the Frog (2009) Disney's return to animated musicals
Rapunzel (2009) Disney's follow up animated musical, though both are listed for 2009, which isn't likely to be right
Some untitled Miles Davis biopic
Nine did not pull up in the search b/c it's not listed with the genre Musical. So, there may be others not included that are in the works.