Question: I have many Linux servers (SUSE 9 &10) used to run web services that provide data to large calculation grids. Recently we have had some difficult to explain outages (i.e. hardware and software logs are not showing any obvious errors) and we are starting to wonder whether the long uptime (typically 200-300 days) is the issue. Given that these servers are heavily utilised, should I consider a regular reboot cycle?

Answer: 
Linux servers never need to be rebooted unless you **absolutely** need to change the running kernel version. Most problems can be solved by changing a configuration file and restarting a service with an init script.

You need to watch out for reboots... if you changed anything "on the fly" without reflecting your changes in a service's configuration file, those changes will not be applied after a reboot.

I usually reboot after scheduled system updates, though. It's generally not necessary, but I do them when nobody's in the office, so why not? There are often kernel upgrades when I get to doing the update, anyway.
A properly run Linux server should only need rebooting for kernel updates. The same can't always be said for some of the software - for instance, I sometimes have to restart apache2 or mailman.