Guys are doing great things, keep it up! Will your server side stuff always be backed by Tropo or are there plans to make the provider integration more pluggable?
One of the cool things about PhonoSDK is that you can talk to ANY SIP endpoint directly from your web browser. This allows you to actually by-pass Tropo if you wanted to (not sure why you would want to though :)
BTW, You can also attach your Phono app to Voxeo Evolution's IVR hosting platform the same way you connect it to Tropo with an app id!