Current limitation is that Blackberry development can only be taken place in Windows because due to the fact that the Blackberry simulator is an EXE and only executable in Windows. But Mac has a Bootcamp to load Windows so should not be a problem. (While iOS development only supports Mac, and Android development supports both Mac and Windows, stand at the middle.)
Good to hear that Titanium mobile try experimenting integration with Blackberry platform because it greatly reduces the development effort to develop apps targeting these three mobile platforms, and you, as a developer you can just use the web language that you very familiar with need not to learn the native Objective C or Java. I hope this Blackberry supports can be mature soon and I would like to test it out in coming days and to see if it is feasible to use it for my own apps or my works.