That sure didn't take long. Leopard went on sale at 6 p.m. on Friday, and by 5 p.m. on Saturday, we already have a software update recommended for all users, which also requires a restart. It's one thing to be secure in knowing I'm 100% up to date, and quite another thing to have to update my computer on a daily basis.
At least they didn't call it Mac OS X 10.5.1...