The potential data loss issue on system crash when running the ext4 filesystem has recently received wide coverage. Many users expressed the opinion that ext4 should not be more prone to losing data on system crash than ext3 was.
¬† The 2.6.30-rc6 prepatch is out. "Things definitely are calming down, with just about 300 commits in the last week. And most of them are pretty small too, although the powerpc updates brought some defconfig changes that look largish."