I've noticed that raspbmc stores logs on SD card, not in tmpfs. Digging deeper I've discovered it was changed recently as the raspbmc changelog for June update says:
/tmp and /var/log no longer stored in ZRAM tmpfs
I don't understand this decision. SD cards have limited number of write cycles so I would expect raspbmc to store logs out of it.
I am concerned about my SD card lifetime and would like to keep it live as long as possible. Should I move logs directory back to memory filesystem or to external location (I have a NAS server in my network)?