I didn't want to announce anything before the first working version, but I've already started working on an N9 Telegram client, which I'll also release as free software (most probably GPLv3).
Current status: I've successfully integrated the tgl telegram library into my own application; and I'm able to register & log in and received contact list using Qt. I'm going to start working on the UI.

However, I cannot announce any release date currently. I work on it in my free time, so the progress is not fast. It might take a month (or even more) to release the initial version with minimal features. Other features will be added gradually.