Great start - some constructive criticism

My initial reaction is that threadsy does solve a common problem and in a fairly intuitive and easy to use way. Keeping the UI simple (2 panels) makes navigation easy, as well as
providing a good separation between the "inboud" and "unbound" feeds (I'm not too keen on that terminology, but I don't really have a better suggestion.)

As far as constructive criticism of a beta product - I would offer the following thoughts:

1. There is no Loading indicator when the page initially loads. I reloaded the page several times before I checked Firebug to see that requests were being sent and the page was waiting for a response.

2. The "unbound" stream offers an easy way to post simple status updates to facebook and twitter, but does not include the google talk status - that would nice.

3. If people are going to use threadsy as an email client, it needs to have some more features including the ability to CC and BCC. The ability to view an emails full source (including headers) is important as well.

Thats all I've got for now, but it really looks great.

Question about the JS library choice - why choose mootools over a more full featured UI library like ExtJS or Dojo? Seems redundant to recreate a full UI when there are libraries that provide full featured and extensible frameworks to start with. It seems it would have cut back on cross browser compatibility issues and provided more time to add features.

Best Regards-
Mark