After installing Leopard, I had a problem with the battery on my MacBook Pro running down very quickly. Looking at Activity Monitor showed that syslogd was consuming between 90% and 106% of my CPU. Killing the process didn't help, because it would just restart and pick up right where it left off. After shutting down every application and ending all extraneous processes, syslogd was still going crazy.
It turns out that Time Machine performs some sort of logging prior to performing backup operations. I guess the process can get out of hand, which can cause some problems if you are running a laptop on battery. Fortunately, there's a simple fix:
- Disable Time Machine: Go to the Time Machine pane of System Preferences, then set the switch to Off and close System Preferences.
- Kill the syslogd process: Launch Activity Monitor (in /Applications » Utilities), find and select syslogd, and click Quit Process. You will need to authenticate.
[robg adds: I did a bit of searching, and it seems this is more than an isolated incident, though it's not widespread. I would expect that, after killing and restarting syslogd, you could then restart Time Machine. However, since I haven't seen this problem, I can't test this theory.]

