There is an article in the New York Times about how blogs (and Music for Robots in particular) are giving unknown bands exposure:
"[L]ast year, J. P. Connolly, a science teacher in Brooklyn, heard a song by one of his students, a rail-thin 15-year-old named Oliver Ignatius, who is the lead singer for a band called the Hysterics. Mr. Connolly, who had bonded with his student over independent music, loved Mr. Ignatius's song and posted it on Music for Robots, an influential blog he helps run. That's where Joseph Patel, an MTV News producer and regular reader of the blog, heard the song. He also loved it, and decided to put the Hysterics on the air, despite the fact that they had done little more than practice in drummer Geoff Turbeville's parents' bedroom. After the segment was broadcast on MTV, Music for Robots (www.music.for-robots.com) found itself with a new audience: teenage girls, who had come to declare their love for the Hysterics. The band is now in talks with a major label."
This is great, but this story is certainly an anomaly. Blogs or no, there will always be lucky bands who get heard by someone who is influential, but I don't think there will be a replacement anytime soon for working really hard for a really long time at being a band. Of course, that doesn't mean you should send your music to Music for Robots, but you should also be lining up a Monday night gig at that club that lets anyone play and having parties at your practice space.