For all Blackberry mobile device users wanting to use Tasks on your mobile device and sync with Tasks on Google Apps or GMail, there are two ways to accomplish this task:

1. Mobile/Web Access: By logging in with your Blackberry to http://mail.google.com/tasks (you will be prompted to enter your Google Apps full e-mail address and password). This presents a mobile-oriented version of tasks which will directly access your existing tasks via Google Apps.
2. GMTaskSync: A 3rd party application (cost is between $4-$10) available here (Crackberry.com or  Blackberry AppWorld)
   GMTaskSync allows you to bidirectionally  synchronize your Google Apps or G-Mail tasks with with your Blackberry.