Finding out about new composers is very difficult. I was hoping that this forum would help, but it seems people here think that composers like Barber or Copeland or even Schoenberg are still "modern"! Yikes.....
Most of the greats of the last century are recently dead or very old. Part, Feldman, Reich, Glass, Carter, Ligeti, Penderecki, Boulez, Grisey, Stockhausen, Berio etc. The 50's and 60's was really the last, and probably one of the greatest, eras of "Classical" music. These days composers are quick to jump into film composing instead of producing works of art, so I think the game is over.