This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
In blackberry you can develop two different applications i.e. Midlets or Blackberry applications. Blackberry application uses RIM's own libraries. However there are few things which are common to both, like HttpConnections. Recordstore management system etc. The basic difference between two is the user interface part. So prior knowledge of J2ME might be helpful but its not necessary.