The upcoming BlackBerry PlayBook has an operating system that is radically different from the current BlackBerry Platform. Quite simply there is not going to be any support for current BlackBerry Applications to run on the PlayBook, despite RIM’s reluctance to come out and admit it.
Furthermore even when the Java SDK is available on the PlayBook, most BlackBerry applications will need significant porting to bring them over to the new platform. It is possible that the PlayBook will support something closer to desktop Java, then the very special blend of J2ME that BlackBerry Java applications currently run. Even if not, in the Q and A of the last PlayBook development webcast it was revealed that the PlayBook will not have any equivalent of the current BlackBerry menu system, which will result in the underlying java being different, and the fundamental UI of many applications will need to be redesigned.
In the webcast Java developers were encouraged to wait out for the release of the Java SDK, rather then to start learning Adobe Air. However, that does not look like that option is getting the support that it needs from RIM to be viable. The fact is that the future of BlackBerry PlayBook applications is strictly in Flex and WebWorks regardless of if developers like it or not.