Safari 3.0 messed up my G4 OS/X 10.4.9 laptop. After installing it, in iChat I frequently had to type "enter" twice after each input for the message to be sent, and frequently had to type "enter" once to receive a message from someone else.
There were other funky issues, as well. That update modifies system libraries, not just Safari.
And after removing Safari 3.0, everything immediately began working normally (in case you wondered).
So I'm waiting until Leopard to switch to 3.0.
