The property that a hash validates the whole logging chain of all entries before could be used for some interesting things.
Somebody could setup a public logging server that accepts a new hash every minute for a registered system and creates a hash chain of all entries it receives. The storage needed would be pretty small. This is the "write once" media that is practical because it needs to store only one hash per minute.
No information is disclosed to this service other than "i am logging".
Then there could be a recovery cdrom from the distribution which reads the journal of the public service and automatically validates all logs on the system.