I'm about to start GWT on OSX. I come from a typical Textmate/RoR background. Is there anything I should be aware of? Is OSX a bad envrionment to be doing GWT developmenet in?
OSX is a fine environment for developing GWT. I would strongly suggest you use Eclipse, with Google's Plugin for Eclipse which has really nice support for including the GWT SDK, and handling GWT-specific syntax (like native code blocks).