oldepoppemusick Ye Olde Poppe Musicke: Music critic for Slate and the Nation, Jody Rosen.
kylegannonmusic Kyle Gann on Music: Music Critic for the Village Voice, Kyle Gann.
Both are good reads.
A couple of other interesting feeds along the same lines that have been syndicated for a while are:
sashafrerejones S/FJ: Pop music critic for the New Yorker, Sasha Frere-Jones.
therestisnoise The Rest is Noise: Clasical music critic for the New Yorker, Alex Ross.