the init script /etc/init.d/bootmisc creates /var/log/dmesg after boot, and dumps the contents of `dmesg` into this file.
This file is completely unnecessary as all the contents of this file can be fetched by the system logger from /proc/kmsg. Additionally since the system logger can pick this information up, the information logged is then duplicated. Also the information in /proc/kmsg has log priority information, which allows it to be filtered by the system logger.
Also this file doesnt grow, making its use limited since it will only contain information as of when the bootmisc script ran.
In short /var/log/dmesg is unnecessary, and just clutters up the log directory with unwanted information. It should either be removed, or at the least a configuration option added so that it may be disabled.
I'll probably add a option later as it is IMHO useful, e.g. if you use "dmesg -c".
Fixed in c5fb64d61f1462d0f8790838424722e161ba4024