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...