The 2.1 framework will not address the issue Twitter is having. They updated to the 2.0.1 framework, but it's not setup correctly in the application unfortunately.
What really happened is that they were forced to sandbox their application on update most likely. When that happened, they didn't update the Growl framework, and suddenly things just stopped working. They updated the framework in the latest update, but as far as we can tell that didn't address the issue. We've tried contacting them to help them with the problem.
Chris
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Chris Forsythe