Mosque Bombing

Today 20 people were killed in mosque bombings. I'm not Muslim, and though I have muslim friends, I don't pretend to understand everything about their religion or culture. Can anyone shed some light on this? According to my occidental values, churches, mosques, pagodas, etc. are sacred, holy places--havens from the fighting. I know the US refused to go into the mosque inhabited by Al Zarqawi last year. Do these bombings fit into the ethos of Islam? How do they relate to current muslim culture? Are suicide bombers in Iraq who bomb mosques viewed as martyrs or murderes by Iraqis? Thanks for any help.