uptime says my MacBook with Leopard (OS X 10.5.7) has been running for over 21 days now without reboot, and with lots of sleep phases:
9:55 up 21 days, 20:55, 3 users, load averages: 0.47 0.36 0.35
During this time I held a presentation on it, worked on several projects including one over the network with a Windows machine, compiled, installed, updated and deleted lots of software, read, annotated and printed lots of PDFs, restarted my network rooter, synched with my iPhone and updated its software, ran dozens of TimeMachine backups and a partition scan, watched moviews and news, and visited thousands of websites while constantly listening to music and internet radio and getting RSS updates, mails and chatting/talking with friends over three different protocols. And by the way, it’s really hot in Berlin, up to 32°C yesterday – my cooler fan is working a lot currently. Okay, I have to restart Firefox every other day because it eats memory. But the system seems quite unaffected.
I’m really happy to have a laptop/operating system that manages to stay up for three weeks. I rarely reboot my Mac, mostly because of a system update or to boot Windows via BootCamp. Once or twice, I had kernel panic (grayscreen…), or it wouldn’t come out of standby; it’s clearly not stable enough to act as a server, but the most stable system I have ever used.
But “booting” has successfully been replaced by “waking from sleep” for me, which takes about 3 seconds. It is like pushing a Pause button. Windows XP’s hibernate feels also quite stable now, although that may also depend on the drivers of your laptop manufacturer. It’s easier for Apple to ensure stand-by and hibernate stability on their own hardware. And also, “try rebooting” is never an answer on OS X.
Lastly: I think the last time I rebooted was for the latest Safari update. Why do I have to reboot because of a simple browser update? Please, Apple, fix this.