In theory it wouldn't be all that difficult. It would essentially come down to implementing menu-bar integration inside of X11/XQuartz. However, the issue is development isn't focused on the area of keeping the X11/XQuartz problem alive, they are more focused in bringing all of the tools to the Mac natively, meaning using native system calls (instead of X11/XQuartz which essentially emulates the X desktop).
For example, another Linux application known as pidgin can be run natively, without X11/XQuartz AND includes system bar integration. (See system bar icon that doesn't look native.) This is a gtk effort, and not a wine specific one.
This could also be supported by Wine on Mac with a Quartz backend, like the one being developed here.
http://wiki.winehq.o...SX/QuartzDriver However, the last changes made to that version were 3 years ago.
Long story short, I don't see it happening unless someone over at XQuartz decides to implement it. Or maybe it's already implemented (although I've NEVER seen ANY x application take advantage of it). Then it would be up to the wine developers to add some code to access the system tray calls in X11/XQuartz when running on a Mac.