I follow these blogs from time to time for the depth and breadth of information, knowledge and candor. I recommend checking them out:
Arts and culture beat blog from the NY Times - not just for visual arts and an important source for current Big Apple flavah.
A little local shout-out to Regina Hackett's intensive and insightful blog for the Seattle Times/P-I. For a town where painting suffers against the popular trends of installation and raw art, it's a must read.
This LA-based blog was the first city-specific art forum to address the expansive, burgeoning art scene - voted top art blog by Art in America in 2004!