I just installed the OS 10.0.1 update (I work for an Apple premiere developer so we got it a little early).
You will be happy to know system responsiveness (Window / Column resizing, open / close menus, etc) is much more responsive. Still not as good as OS 9 but it is a huge improvement. I don't notice any huge improvement in application launch though. I wish I had more 'in depth' stuff to tell you but I've only just started using it. Sorry I honestly don't know when the update will be released either but I'm sure it will be soon.
(I'm running a biege G3 333 with 320 MB of RAM)
Thanks