In the DAWs I have tested on OSX, the VST SDK wrapper is not accepting text input.
I am on OSX 10.8.devel with latest tip from a week ago. Xcode Version 4.6.3 (4H1503).
I know there was a problem with Live stealing keypresses, but thought that was the only one - which hosts are you talking about? Or is it something simple like you’ve not set the JucePlugin_EditorRequiresKeyboardFocus flag?