WILLIAM25 This is the reply received from Agile. It doesn't work right out of the box. You have to hack it with a text editor. They are working on an update.
Thanks for taking the time to contact us. Apple surprised us a bit by introducing the Safari 4 public beta today. We're working on a new release that will officially support Safari 4, but you can already enable it if you like. We have a post in our forums that details how to do it. If you think you messed anything up, you can simply download from our website and start fresh.
I hope this information helps. We'll have an official release with Safari 4 support soon.
(Version 4.0b1)