nandwrite -p /dev/mtd2 /ubuntu-9.0.5.Release.jffs2
nandwrite -m /dev/mtd2 /ubuntu-9.0.5.Release.jffs2
nandwrite -pm /dev/mtd2 /ubuntu-9.0.5.Release.jffs2
nandwrite /dev/mtd2 /ubuntu-9.0.5.Release.jffs2
nandwrite --help explains the options
-p pad to page size. The JFFS2 image is already padded. but the kernel is not. Use it for kernel writes.
-m mark blocks bad if the write fails. Seems appropriate to use for both kernel and file system.