Please really need it are you planning to develop it?
we're planning to develop native apps for most popular phones incl. Blackberry.
You're welcome to add a request to our Votebox: http://todoist.com/Vote/
For now, please note that you can access the Todoist Mobile site: http://todoist.com/m through any HTML5 compatible mobile browser.
Any updates on the release? At least playbook. Version?