Sorry for the necro, but I had a bit of an interest in this.
I don’t suppose you’re consider an open-source approach to clients, are you?
Open format, open upload API, maybe even open client?
I figure that with Adobe Air being all but impossible to install from Adobe directly (I spent about an hour finding an installer the last time, in April), new users are having an increasingly harder time getting up and running with the current client.
I don’t mean to sound like a doomsayer, but it seems to me that the need for a new client is approaching very quickly.