Using LABEL: in fstab instead of a /dev/hd* entry is a very bad idea because many people (myself included) have several Linux installs on the same machine. When I do an upgrade, I keep the old version and install the new version on different partitions (keeping only /home and /usr/local) so I can go back to the old OS if necessary. What happens when there are two or three partitions with the label "/usr"?
The install checks all type 0x83 partitions for labels to make sure that it is using unique labels. If a / already exists, for example, the new / will be label'd /1. Similiar changes happen for /usr, and to avoid /usr/share/something/or/other and /usr/share/something/or/this from having the same label after being truncated to fit in the superblock. Yes, this has all been tested ;-)