EHeap2 - Excellent, fast, and ideal for our interapplication and intersystem communications. Works reliably under MacOS X and Windows 2000
Data Heap - Sounds like it would be ideal for passing data between applications and systems in a cross-platform manner. We ultimately will want to use it for passing information (sketches, pictures, etc.) between the SketchClient and the Mural (in their various incarnations.) Because it's not yet available, we've been forced to use other workarounds; mainly, we've had the client place information to be shared in a web-accessible directory (courtesy of Apache), and then place the relevent URL in the contents of a "PostPicture" event.
Cocoa - Allows nearly-effortless access to pressure information for Wacom tablets, which could allow for nicer-looking sketches from the SketchClient. Cocoa-Java allows for easy integration of EHeap2 technology. Unfortunately, Cocoa isn't exactly cross-platform portable.
Java 1.3 - Works fine on Mac OS X, but graphics are flickery and unsightly on Windows 2000. Still, for native integration with the EHeap2, it doesn't get any better than this. Except, of course, for...
Java 1.4 - Not available on Mac OS X, but available in beta for Windows 2000. Provides great image and 2D graphics speed and quality. And if you really want Mac OS X support, back-porting from 1.4 to 1.3 is a trivial proposition, involving changing a few well-isolated lines of code and recompiling.