or, if using syslog-ng, do this for each logfile type in your config file:
destination syslog { file("/var/log/serverlogs/$HOST/syslog" owner("root") group("adm") perm(0640)); };
that way, each server will have unique files in their own directories.
I'm assuming you mean maintaining a separate log per machine that you collect logs for? I wouldn't bother with that, personally. Grep is a great tool... If you *really* generate a lot of log information and need to analyze it in greater detail, then dumping it into a database at the back end could be warranted. For most sites, though, grep is quite sufficient, especially if you combine it with swatch -- which can look through your log files for particular events that you define, and then email/page you when/if they occur. A simple, but quite usable intrusion detection system of sorts...