The Full catalog and most of the speakers for the Ignite conference have been posted. You can find the most up to date list here: Sessions and Speakers. Also I recommend reviewing the Exchange Team Blog at EHLO Blog which highlights the Exchange and Office 365 related sessions at Ignite!
While I was not selected as a speaker for a full sessions, I will be present at Ignite and hopefully working a bit in the Office Division Booth as well being available for discussions or questions in the Expo Hall Area! I am really looking forward to the Ignite conference, if you have not already registered, go now and get signed up: http://ignite.microsoft.com/