I want to code up a panel that will be used both in Linux and Windows. Ideally it will be written in Python using PyQT.
What I've found so far is the QSystemTrayIcon widget, and while that is quite useful, that's not quite what I'm looking for. That widget lets you attach a menu to the left and right clicks of an icon on the system tray and then you can have a dialog open in certain situations.
I'm looking for something that will let me write up something like the tools that Gnome lets you add to the taskbar (they call them panels). Such as a weather feed, or processor usage, right on the taskbar. And also not in the system tray area.
I'm writing more of a tool than something reflects a status.
I know that I could write this natively in both OSes using GTK and its ilk, but anyway to write in PyQT or WxWidget so I don't have to deal with dependancy issues?
Widgets inside the GNOME panel are called applets, and to my knowledge it's not possible to write them with anything but Gtk, since you have to use the respective GNOME library libpanel-applet (in either C, C++ or Python). 
System tray icons are different, because they only allow icons to be displayed inside the notification area, since Windows only supports icons there. 
The panel mechanism on Windows (Vista, XP does only have the notification area) is quite different, I would assume. Unless somebody already wrote a library that abstracts the differences of the GNOME panel and the Vista side bar, you would have to do that yourself.
Python taskbar applet