Major updates were applied on all our servers, ending with a mandatory kernel update to 2.6.9-55. Good old bravo and charlie servers are the last in line to be rebooted, with a very decent uptime:

gupi@bravo [~]# uptime
22:03:13 up 278 days, 16:41, 1 user, load average: 0.07, 0.23, 0.17
gupi@charlie [~]# uptime
22:03:42 up 278 days, 16:19, 1 user, load average: 0.10, 0.08, 0.08

No major downtime occured and all services are working smooth.

Eventually, another big challenge will follow in a few months, in order to migrate to CentOS 5.* without moving the accounts between servers. But this is another story.