Mac OS X 10.4.10 is available immediately. You can get it through Software Update (under your blue Apple menu) or by visiting http://www.apple.com/support/downloads.
As is usually the case, there is a "standard" updater which requires 10.4.9, or a "combo" updater for versions 10.4.0 through 10.4.8. There are separate "standard" and "combo" installers for PPC Macs, Intel Macs, PPC Mac servers, and Intel Mac servers. Be sure to select the one that goes with your machine.
And as always, remember to back up your important data *before* updating, and to repair permissions *after* updating.