There are now 2 primary development platforms for BlackBerry.
The BlackBerry OS is the OS used on BlackBerry Smartphones. BlackBerry OS is Java based. Although BlackBerry applications can be developed on any platform(Linux, OSX etc), the best supported is the Windows 32bit platform. You will also need BlackBerry Eclipse Plug-in and BlackBerry Java Development Environtment(JDE). BB OS 7.1 was released in Jan 2012.
BlackBerry PlayBook OS is a QNX based OS for the BlackBerry Playbook Tablet. BB10 is the next evolution of the QNX based OS for both the tablet and future BlackBerry smartphones.
If you are just developing for the Smartphones you can build using Java.
If you are just developing for the Playbook you can use Adobe Air or BlackBerry Native SDK (C/C++).
For BOTH you can use Html 5 or Webworks (compile Html 5 apps).
for more info go here: http://developer.blackberry.com and select the approach you prefer.
check the forums and devblog (http://devblog.blackberry.com/) for other tips and samples.
SAP SUP supports building java apps for the BlackBerry Smartphone. The main SDN landing page for mobile has more info on SUP. They currently don't have support for the Playbook.