Maybe
1.1. Back up using Time Machine - Just in case. It is upgrading system files, anything can go wrong.
2. Wait till a few have got the retail discs
3. Check the Mac OS forum for problems
4. Pop in Snow Leopard
5. Click "Install"
6. Go through basic questions to install, upgrade is fine. (Other options might be more confusing. This is best if you want an easy upgade.)
7. Wait
8. If there's an issue - hit Macrumors for a solution.
8. Enjoy Snow Leopard
? I guess the need for a forced reboot a couple of times after the 10.5.8 update makes me a little wary of saying everyone's got plain sailling!