Update: This is fixed in Speed Download 4.1.12
Suckers Early adopters like me have already downloaded the Safari 3.0 beta, because it pays to be super cool like us. However, it’s hard to be awesome when your browser crashes on startup, like mine was. It looks like the Speed Download plugin I had installed was at fault.
To remove it, I went to
<My Home Directory>/Library/InputManagers/ and trashed the
SpeedDownload Enhancer folder. Now Safari 3.0 starts nicely.