wxPython GUI on a web page?
You can use Javascript to create your own GUI to show. Maybe Google's NaCl is far enough advanced but it won't give you the cross browser compatibility you'll probably like.
If you look at broadway (which is linked in one of the other answers), you'll need to run an X session for each user.
Is it possible to embed a wxPython based GUI in an HTML page?
If not, is there any other option other than Java applets to make GUIs that can be embedded onto an HTML page?